LIBRARY 
G 


LABORATORY  EXERCISES 


IN 


ANATOMY  AND  PHYSIOLOGY 


JAMES  EDWARD  PEABODY,  A.M. 

Instructor  in  Biology  in 
The  Morris  High  School,  New  York  City 


SECOND  EDITION,  REVISED 


NEW  YORK 

HENRY  HOLT  AND  COMPANY 
1906 


Copyright,  1898, 1902, 

BY 

HENEY  HOLT  &  CO. 


ROBERT  DRT7MMOND.   PRINTER,   NBTW  YORK 


PEEFACE. 

EVERY  pupil  in  the  study  of  human  physiology  should 
be  led  to  see  that  most  of  the  materials  required  for  ob- 
servation and  experiment  in  this  subject  are  furnished  by 
the  organs  and  tissues  of  his  own  body.  The  following 
laboratory  directions  aim  primarily  to  familiarize  the  pupil 
with  the  working  of  his  own  organs  of  motion,  circulation, 
respiration,  and  digestion.  Much  of  the  necessary  sup- 
plementary material  (soup-bones,  meat,  foods,  etc.)  can  be 
easily  obtained  by  the  student.  The  pieces  of  apparatus 
needed  for  the  class  demonstrations  and  experiments  (test- 
tubes,  bell-jars,  thistle-tubes)  are  usually  found  in  the 
chemical  or  physical  laboratory  of  the  school. 

At  the  beginning  of  each  topic  of  study  I  have  given 
directions  which  in  my  experience  have  been  found  neces- 
sary to  guide  the  pupil  in  his  observations  and  experi- 
mjejits.  The  questions  which  follow  these  directions  have 
been  framed  with  the  object  of  leading  the  student  to  seek 
the  facts  from  the  material  itself.  The  student  should  be 
trained  especially  to  distinguish  in  the  experiments  observed 
results  from  the  inferences  that  may  be  drawn  from  those 
results. 

I  have  found  that  a  considerable  amount  of  laboratory 
work  can  be  profitably  done  by  the  pupil  at  home  and 
reported  in  class  at  the  next  recitation  period.  Hence  it 
is  possible  to  carry  on  experimental  work  in  the  large 
classes  of  the  first  year  of  the  high  school  more  satisfactorily 
in  biology  than  in  any  other  subject.  The  exercises  that 

iii 


304680 


IV  PREFACE. 

can  be  prepared  at  home  to  good  advantage  are  Nos.  4,  6, 
7  (last  half),  9,  10,  13,  14,  15  (first  half),  16,  17,  24,  29, 
31,  32,  33,  36,  41,  42,  43,  45,  46,  and  the  larger  part  of 
48  and  49.  Whenever  the  abbreviation  (Dem.)  is  found 
in  any  part  of  an  experiment,  a  demonstration  will  be 
given  by  the  instructor. 

The  most  satisfactory  method  of  recording  laboratory 
work  I  find  to  be  this.  The  observations  and  conclusions 
are  stated  briefly  by  the  pupil  in  his  note-book  as  the  work 
is  done.  Some  little  time  is  taken  for  discussion  at  the 
close  of  the  period,  when  the  facts  are  clearest  in  mind, 
special  care  being  taken  to  see  that  correct  inferences  have 
been  drawn.  That  the  work  of  the  day  may  be  more 
firmly  fixed  in  the  pupil's  mind,  he  is  required  to  write  on 
paper  of  a  certain  kind  and  size,  and  to  present  at  the  next 
lesson  a  carefully  prepared  statement  of  (1)  the  steps  in  the 
experiment,  (2)  the  results  observed,  (3)  the  conclusions 
which  were  drawn  from  the  experiment.  These  papers, 
together  with  the  drawings  and  other  work  prepared  in 
class,  are  arranged  in  a  cover  belonging  to  each  pupil,  and 
constitute  his  laboratory  book. 

The  descriptive  terms  dorsal  and  ventral,  anterior  and 
posterior,  median  and  lateral,  employed  in  comparative 
anatomy,  are  used  in  the  following  directions,  since  they 
seem  preferable  to  the  more  indefinite  terms  front  and 
back,  upper  and  lower,  middle  and  side,  commonly  used 
in  books  on  human  physiology.  I  have  adopted  through- 
out the  food  study  the  term  nutrients  (for  food-materials, 
foodstuffs),  and  nitrogenous  substances  (for  proteids,  albu- 
minoids, gelatinoids,  etc.);  these  terms  are  used  in  the 
publications  of  the  II.  S.  Department  of  Agriculture. 

We  have  found  the  study  of  the  material  at  the  American 
Museum  of  Natural  History  (especially  the  skeletons  and 


PREFACE.  V 

teeth  of  mammals)  and  of  the  animals  in  the  Zoological 
Park  a  valuable  means  of  review  and  of  awakening  inter- 
est in  the  subject.  With  a  definite  list  of  questions  (see 
pp.  73  and  107)  in  the  hands  of  each  pupil  a  division  of 
thirty  to  fifty  can  be  directed  in  this  work.  Time  should 
be  taken  at  the  close  of  such  study  for  a  comparison  of 
notes  and  for  general  discussion. 

Some  knowledge  of  the  cell  is  so  essential  to  any  intelli- 
gent comprehension  of  the  subject  of  human  physiology 
that  it  seems  necessary  to  introduce  frequent  discussions  of 
protoplasm  and  its  properties.  Circulating  protoplasm  is 
easily  demonstrated  in  the  cells  of  the  plant  Nitella  or 
Elodea.  Epithelium  (including  gland  and  ciliated),  muscle 
and  nerve  cells  should  be  shown  if  possible.  The  study  of 
yeast  and  bacteria  is  suggested  to  give  the  pupil  some 
acquaintance  with  the  physiology  of  the  cell,  as  well  as  a 
series  of  facts  relating  to  these  organisms. 

Since  physiology  precedes  physics  and  chemistry  in  the 
ordinary  high  school  courses  of  study,  it  is  necessary  to 
give  the  pupil  a  few  ideas  of  the  fundamental  principles 
of  these  subjects.  It  seems  wise  to  discuss  oxidation  and 
its  products  more  or  less  thoroughly,  and  to  dwell  upon  os- 
mosis, atmospheric  pressure,  and  the  properties  of  acids  and 
alkalis.  The  structure  and  physiology  of  the  organs  of 
special  sense  (eye,  ear),  as  well  as  the  thorough  consider- 
ation of  levers,  should  be  omitted,  in  my  judgment,  until 
after  a  course  in  physics  has  been  taken. 

It  is  not  expected  that  all  of  the  following  experiments 
will  be  performed  in  the  limited  time  usually  assigned  in 
the  curriculum  to  this  subject.  The  exercises  are,  how- 
ever, sufficiently  varied  to  allow  a  wide  range  of  choice. 
The  laboratory  work  on  a  given  topic  should,  if  possible, 
be  given  before  the  study  of  that  topic  in  the  text-book, 


vi  PREFACE. 

The  teacher  will  find  the  following  reference-books  to 
be  valuable  in  experimental  physiology:  Stirling's  "  Out- 
lines of  Practical  Physiology"  (P.  Blakiston,  Son  &  Co., 
Philadelphia);  Foster  and  Langley's  " Practical  Physi- 
ology" (The  Macmillan  Co.,  New  York);  Klein's  "Micro- 
Organisms  and  Disease"  (The  Macmillan  Co.,  New  York). 
Additional  exercises  are  suggested  in  "Outlines  of  Ke- 
quirements  in  Anatomy,  Physiology,  and  Hygiene "  (Har- 
vard University). 

Suggestions  for  many  of  the  following  exercises  were 
found  in  the  publications  of  J.  Y.  Bergen,  B.  P.  Colton, 
H.  Newell  Martin,  H.  P.  Bowditch,  M.D.,  and  in  the 
books  mentioned  above.  Much  of  'the  outline  for  the 
study  of  bacteria  was  suggested  by  Dr.  T.  M.  Pruden, 
College  of  Physicians  and  Surgeons,  N.  Y.  Many  valuable 
suggestions  have  been  given  by  Dr.  C.  B.  Davenport  of 
Harvard  University.  I  am  especially  indebted  to  Dr. 
Margaret  B.  Wilson  of  the  N.  Y.  Normal  College  for 
careful  criticism  of  my  manuscript,  and  to  my  colleagues 
in  the  biological  department  of  the  school  for  their  sug- 
gestions. 

The  cut  of  the  microscope  on  p.  109  was  kindly  loaned 
by  Bausch  &  Lomb  Optical  Company.  Most  of  the  other 
illustrations  were  prepared  from  drawings  made  by  one  of 
my  first-year  pupils,  Miss  Marietta  P.  Gates. 

J.  E.  P. 

THE  MOKRIS  HIGH  SCHOOL, 
YORK  CITY,  Oct.  1,  190£. 


TABLE   OF  CONTENTS. 

PAGK 

I.  LESSONS  IN  PHYSICS  AND  CHEMISTRY. 

1.  Study  of  a  Match 1 

2.  Study  of  Oxygen 5 

3.  Study  of  Air 9 

4.  Study  of  Atmospheric  Pressure 12 

5.  Study  of  Hydrogen 13 

6.  Study  of  Evaporation  — 16 

7.  Acid,  Alkaline,  and  Neutral  Substances 17 

II.  FOODS. 

8.  To  Determine  the  Amount  of  Water  in  Foods 19 

9.  To  Test  Foods  for  Starch 20 

10.  To  Test  Foods  for  Grape-sugar 22 

11.  To  Test  Foods  for  Nitrogenous  Substances  (Pro- 

teids) 23 

12.  To  Test  Foods  for  Fats  and  Oils 26 

13.  To  Test  Foods  for  Mineral  Matters 27 

14.  Analysis  of  Flour 27 

15.  Study  of  Milk 29 

16.  Study  of  Food  Charts 31 

III.  DIGESTION  AND  ABSORPTION. 

17.  Study  of  the  Mouth 33 

18.  To  Prepare  Artificial  Digestive  Juices 35 

19.  Digestion  of  Starch 37 

20.  Digestion  of  Mineral  Substances 38 

21.  Digestion  of  Nitrogenous  Substances 39 

22.  Digestion  of  Fats 42 

23.  Principles  of  Osmosis 45 

24.  Outline  for  Recording  the  Digestion  of  the  Nutri- 

ents   49 

vii 


TABLE  OF  CONTENTS. 


IV.  THE  BLOOD  AND  CIRCULATION. 

25.  Study  of  Beef  Blood. . ; 50 

26.  Microscopic  Study  of  Blood  Corpuscles 58 

27.  Study  of  a  Beef  Heart. 54 

28.  Circulation  of  Blood    in   the    Tail  of  a  Tad- 

pole    56 

29.  Pulse  in  the  Pupil's  own  Body 57 

V.  THE  SKELETON  AND  THE  MUSCLES. 

30.  Structure  of  Bones 58 

31.  Composition  of  Bones 60 

32.  Classification  of  Bones 62 

33.  Study  of  the  Muscles 62 

34.  Study  of  Beefsteak 67 

35.  Structure  of  a  Joint 68 

36.  Study  of  the  Joints  in  the  Body ,  70 

37.  Comparative  Study  of  Mammalian  Skeletons. . .  73 
VI.  RESPIRATION. 

38.  Action  of  the  Diaphragm  and  Lungs 75 

39.  Circulation  of  Air  in  the  School- room 77 

40.  Inspired  and  Expired  Air. 78 

41.  Temperature  of  the  Body 80 

VII.  THE  SKIN  AND  THE  KIDNEYS. 

42.  Study  of  the  Skin . .  -. 80 

43.  Study  of  Excretion 83 

44.  Study  of  a  Sheep's  Kidney 84 

VIII.  NERVOUS  SYSTEM. 

45.  Sensations  of  Touch 86 

46.  Sensations  of  Taste  and  Smell 88 

47.  Study  of  a  Sheep's  Brain 90 

IX.  SUPPLEMENTARY  WORK. 

48.  Study  of  Yeast 94 

49.  Study  of  Bacteria 100 

50.  Study  of  Living  Vertebrates 107 

X.  THE  COMPOUND  MICROSCOPE. 

51.  Parts  of  the  Compound  Microscope 108 

52.  Rules  for  the  Use  of  the  Compound  Microscope.  112 
XI.  LIST  OF    APPARATUS  AND  CHEMICALS    FOR  CLASS  OF 

TWENTY-FOUR,.                                                       .  115 


LABORATORY   EXERCISES 


ANATOMY  AND  PHYSIOLOGY 

4 

(The  abbreviation  (Dem.)  means  that  a  demonstration  will  be 
given  by  the  instructor. ) 

i.   STUDY  OF  A  MATCH. 

Materials :  Sulphur-matches,    phosphorus,    sulphur,  lime-water, 
bottle  and  stopper,  tumbler,  pieces  of  board. 

A.  Phosphorus. 

1.  Rub  the  end  of  a  sulphur-match  on  your 

finger  in  the  dark.     What  is   the  ap 
pearance  of  the  streak? 

2.  Light  a  match  by  rubbing  the  tip  on  a 

rough  surface.  What  is  the  color  of  the 
flame  at  first?  Describe  the  color  and 
smell  of  the  fumes  that  first  go  off  into 
the  air.  (These  fumes  are  called  oxid 
of  phosphorus.) 

3.  (Dem.)  Observe    the    instructor    while   he 

cuts  off  a  piece  of  phosphorus.    (Caution! 

Phosphorus  must  never  be  handled  with 

the  fingers.) 

a.  What  are  some  of  the  physical  prop- 
erties (color,  odor,  hardness)  of 
phosphorus  ? 


2  .LABORATORY  EXERCISES. 

b.  Compare  the  smell  of  the  phosphorus 
with  the  smell  of  the  match  tip  in 
i  (above).  What,  therefore,  is 
one  of  the  substances  found  in  the 
head  of  a  match? 

4.  (Dem.)  After  the  water  has  been  removed 

from  the  phosphorus  by  means  of 
blotting-paper,  what  do  you  observe? 
In  what  other  part  of  this  experiment 
have  you  observed  a  similar  substance? 
Why  is  phosphorus  kept  under  water? 

5.  (Dem.)  What  is  the  result  of  rubbing  a 

piece  of  phosphorus  between  two  sticks 
of  wood?  What  causes  this  result  to 
take  place?  (To  aid  in  answering  this 
question  rub  together  briskly  your  two 
hands  and  note  the  feeling.)  (When 
phosphorus  burns  it  combines  with  the 
oxygen  gas  found  in  the  air  and  forms 
oxid  of  phosphorus.)  How  was  the 
phosphorus  made  to  combine  with  oxy- 
gen? 
B.  Sulphur. 

1.  Examine    some    common    sulphur.     What 

are  its  physical  properties?  What  evi- 
dence of  sulphur  can  you  see  near  the 
match  tip? 

2.  Light  another  match,  and  after  the  white 

fumes  have  disappeared,  smell  cautiously 
of  the  burning  match  head.  (This  gas 
is  called  oxid  of  sulphur.)  What  kind 
of  odor  has  the  gas? 


STUDY  OF  A   MAZCK.  '    $ 

3.  (Dem.)  Light  some  sulphur  with  a  heated 

wire.  What  is  the  color  of  the  flame? 
Notice  the  smell  of  the  burning  sulphur. 
In  what  other  part  of  this  experiment 
have  you  noticed  a  similar  odor?  (When 
sulphur  burns  it  combines  with  the  oxy- 
gen gas  of  the  air,  forming  oxid  of  sul- 
phur.) 

4.  (Dem.)  Rub  a  bit  of  sulphur  between  two 

pieces  of  wood,  as  was  done  with  the 
phosphorus.  What  do  you  observe? 
Why,  then,  is  phosphorus  put  on  the  end 
of  a  match? 

C.  Water. 

1.  After  the  wood  of  a  match  is  burning  well, 

hold  it  a  little  distance  beneath  the 
mouth  of  an  inverted  dry  tumbler.  What 
do  you  see  on  the  sides  of  the  glass? 

2.  What  is  one  of  the  substances,  therefore, 

that  is  formed  when  wood  burns?  Why 
is  the  tumbler  used  in  this  experiment? 

D.  Carbon. 

1.  When  the  wood  of  the  match  has  been 

charred,  extinguish  the  flame.  (The 
substance  left  is  called  charcoal  or  car- 
bon.) What  are  some  of  the  physical 
properties  of  carbon? 

2.  Heat  the  carbon  red  hot.     Does  it  burn? 

How  do  you  know? 

3.  (Dem.)  Thrust  a  piece  of  wood  through  a 

hole  in  the  stopper  that  fits  tightly  in 
the  mouth  of  a  bottle.  Light  the  wood, 


4  LABORATORY  EXERCISES. 

and  insert  the  burning  piece  of  carbon 
into  the  bottle,  closing  the  mouth  with 
the  stopper.  What  do  you  observe? 
Suggest  an  explanation  of  this  fact. 
4.  (Dem.)  Remove  the  stick,  pour  into  the 
bottle  a  little  clear  lime-water,  and 
shake.  What  change  do  you  observe 
in  the  lime-water?  (When  carbon  burns 
it  combines  with  the  oxygen  gas  of  the 
air,  forming  oxid  of  carbon,  more  com- 
monly known  as  carbonic-acid  gas  or 
carbon  dioxid.)  How,  then,  can  the 
presence  of  carbon  dioxid  be  demon- 
strated? 

E.  Mineral  matters. 

1.  Burn  a  match  as  long  as  you  can.     What 

are  some  of  the  physical  properties  of 
the  ashes?  (The  ashes  represent  the 
mineral  matter  of  the  wood,  carried  up 
from  the  earth  in  the  sap.  When  the 
water  of  the  sap  evaporated,  the  solid 
substances  were  left  behind  as  a  part  of 
the  wood.) 

2.  Heat  these  mineral  matters  as  hot  as  you 

can.     Will  they  burn? 

3.  How     could     you     determine,     therefore, 

whether  or  not  a  substance  contained 
mineral  matter? 

F.  Summary. 

i.  Name  in  order  the  parts  of  a  match  that 
will  burn,  beginning  with  the  most  in- 
flammable. 


STUDY  OF  OXYGEN.  5 

2.  'Name  the  substance  produced  by  the  burn- 

ing of  each  of  the  above  ingredients,  and 
state  how  each  can  be  recognized. 

3.  What  are  the  ingredients  of  a  match  that 

will  not  burn? 


2.  STUDY  OF  OXYGEN.      (Dem.) 

Materials :  Apparatus-stand,  test-tube  with  perforated  stopper, 
delivery-tube,  tray  of  water,  five  bottles,  a  piece  of  glass  to  cover 
each  bottle;  potassium  chlorate,  black  oxid  of  manganese,  phos- 
phorus, sulphur,  splinters  of  wood,  piece  of  picture-wire,  piece  of 
crayon. 

A.  Preparation  of  oxygen. 

1.  Mix   a    spoonful   of   pulverized   potassium 

chlorate  with  one-fourth  this  amount  of 
black  oxid  of  manganese.  Put  the  mix- 
ture in  a  test-tube,  and  attach  it  to  an 
apparatus-stand  in  a  slanting  position. 
Close  the  mouth  of  the  tube  with  a  stop- 
per through  which  passes  a  delivery-tube. 
The  other  end  of  the  delivery-tube 
should  run  beneath  the  surface  of  the 
water  in  the  tray.  (See  Fig.  i.) 

a.  Heat  the  test-tube  gently.     What  do 

you  observe? 

b.  Potassium  chlorate  and  oxid  of  man- 

ganese contain  a  large  amount  of 
oxygen.  How  are  these  com- 
pounds made  to  give  up  oxygen? 

2.  Fill  the  four  bottles  with  water  and  cover 

each  with  a  piece  of  glass.  Invert  one 
in  the  pan  of  water  over  the  end  of  the 


6  LABORATORY  EXERCISES. 

delivery-tube    and    remove     the    glass 
cover. 

a.  Why   does   the   bottle   remain   filled 

with  water?     (See  experiment  4.) 

b.  Continue  to  heat  slowly  the  mixture 

in  the  test-tube.  What  do  you 
observe?  Does  oxygen  dissolve 
readily  in  water?  How  do  you 
know? 

3.  When  the  escaping  oxygen  has  filled  the 
bottle,  cover  it  with  the  glass  plate,  re- 
move it  from  the  tray,  and  turn  it  right 
side  up.  Fill  the  other  bottles  in  the 
same  way.  Why  is  the  glass  cover 
placed  over  each  bottle? 


FIG. 


To  obtain  pure  oxygen  the  gas  should  be 
run  through  two  bottles  as  shown  in  Fig. 
i.  Place  in  the  first  water,  and  in  the 
second  a  solution  of  caustic  soda.  These 
liquids  absorb  most  impurities.  When 
the  oxygen  has  been  washed  in  this  way, 


STUDY  OF  OXYGEN.  7 

collect  it  in  a  fifth  bottle  as  described  in 
2  and  3  above. 
B.  Properties  of  oxygen. 

1.  What  is  the  color  of  the  oxygen  obtained 

in  4  above?  Remove  the  glass  cover 
from  the  bottle  and  smell  of  it.  What 
do  you  find?  Inhale  some  of  the  gas 
through  the  mouth.  Has  it  any  taste? 
Enumerate,  therefore,  some  of  the  phys- 
ical properties  (color,  taste,  odor)  of 
oxygen.  What  are  the  physical  proper- 
ties of  the  oxygen  in  the  air? 

2.  Prepare  a  burning  spoon  by  tying  a  wire 

about  a  small  piece  of  crayon.  Place 
upon  the  top  of  the  crayon  some  phos- 
•phorus  and  light  it.  Remove  the  glass 
cover  from  the  top  of  one  of  the  bottles 
of  oxygen  and  lower  into  it  the  burning 
phosphorus. 

a.  What  do  you  observe?     Does  phos- 

phorus burn  better  in  air  or  in 
oxygen?  What  is  the  color  of  the 
flame? 

b.  What  do  you  see  in  the  jar  in  which 

the  phosphorus  has  been  burning? 
Name  this  compound.  (Compare 
experiments  J,  A,  2,  4,  5.) 

3.  Into  a  second  bottle  of  oxygen  lower  some 

burning  sulphur. 

a.  What  do  you  observe?  Does  sul- 
phur burn  better  in  air  or  in  oxy- 
gen? 


LABORATORY  EXERCISES. 

b.  When  the  flame  is  extinguished  cover 
the  bottle  with  the  glass.  Cau- 
tiously smell  of  it.  What  is  the 
gas?  (Compare  with  experiments 
f,  B,  i,  3.)  What  are  the  phys- 
ical properties  of  this  gas? 

4.  Thrust  a  burning  stick  into  a  third  bottle 

of  oxygen. 

a.  What  do  you  observe? 

b.  Remove  the  stick  quickly  and  blow 

out  the  flame,  leaving  a  glowing 
end.  Again  thrust  the  stick  into 
the  jar  of  oxygen.  What  is  the 
result  ? 

c.  Repeat  the  preceding  experiment  sev- 

eral times.  What  do  you  finally 
observe?  Explain  this  fact. 

d.  Into  the  bottle  put  some  clear  lime- 

water  and  shake.  What  is  the  re- 
sult and  what  do  you  infer  ?  (Com- 
pare experiment  J,  D,  4.) 

5.  Heat  the  end  of  a  picture-wire  and  dip  it 

into  sulphur.  When  the  little  ball  of 
sulphur  is  burning  well,  lower  the  heated 
picture-wire  into  the  fourth  jar  of  oxy- 
gen. Describe  the  result.  Will  iron 
burn  in  the  air? 

6.  Did  the  oxygen  burn  in  any  of  the  preced- 

ing experiments?  Does  the  oxygen  of 
the  air  ever  catch  fire?  How  do  you 
know?  What,  then,  does  the  oxygen  do 
in  each  experiment? 


STUDY  OF  AIR.  9 

7.  (By  burning  or  oxidation  is  meant  the  chem- 
ical union  between  oxygen  and  some 
other  substance.)  How  can  you  tell 
when  oxidation  is  going  on?  Name  the 
compounds  that  have  been  formed  by 
oxidation  in  the  preceding  experiments. 

3.    STUDY  OF  AIR.       (Dem.) 

Materials :  Tray  of  water,  flat  piece  of  cork  about  two  inches  in 
diameter,  small  porcelain  dish  (or  bit  of  crockery),  phosphorus,  glass 
jar  with  wide  mouth,  piece  of  glass  to  cover  the  jar,  cylindrical  grad- 
uate. 

A.  Preparation  of  nitrogen. 

i.  Place  the  porcelain  dish  (or  piece  of  crock- 
ery) on  the  piece  of  cork  and  float  the 
latter  on  the  water  in  the  tray.  Into 
the  dish  put  a  piece  of  phosphorus  twice 
the  size  of  a  pea.  Light  the  phosphorus 
and  then  quickly  cover  it  with  the  in- 
verted glass  jar,  keeping  the  rim  of  the 
latter  about  an  inch  below  the  surface  of 
the  water.  (See  Fig.  2.) 

a.  With  what  was  the  jar  filled  when  it 

was  placed  over  the  burning  phos- 
phorus? 

b.  As  the  phosphorus  burns  what  do  you 

see  within  the  jar?  What  is  the 
composition  of  this  substance? 
How  was  it  formed?  (See  Exp. 
1,  A,  5.) 

c.  What  ingredient,  therefore,  of  the  air 

is  being  removed?     Why  does  the 


10  LABORATORY  EXERCISES. 


phosphorus  after  a  time  cease  to 
burn? 

What  change  do  you  see  in  the  level 
of  the  water  within  the  glass  jar? 
How  do  you  explain  this?  (See 
Exp.  4.) 


FIG.  2. 

e.  What  change  do  you  see  in  the  com- 
pound that  was  formed  within  the 
glass  jar?  Explain. 

2.  Slide  a  piece  of  glass  beneath  the  mouth  of 
the  bottle,  turn  the  latter  right  side  up, 
taking  care  not  to  lose  any  of  the  water 
that  has  risen  in  the  jar.  The  ingredient 
of  the  air  left  in  the  bottle  is  nitrogen. 
Keep  the  bottle  covered  and  shake  the 
water  about  to  wash  the  nitrogen  as 
much  as  possible. 

a.  Drop  a  piece  of  blue  litmus  paper 
(see  experiment  7)  into  the  water. 
What  change  do  you  see?  (This 
proves  that  oxid  of  phosphorus 
makes  water  acid.)  • 
B.  Properties  of  nitrogen. 

i.  What  are  the  physical  properties  of  the 
nitrogen  in  the  bottle?  What  are  the 


STUDY  Of  AIR.  11 

physical  properties  of  nitrogen  in  the 
air?  Is,  therefore,  the  nitrogen  in  the 
bottle  pure? 

2.  Place  a  piece  of  phosphorus  on  the  burning 

spoon  and  light  it.  Carefully  remove 
the  glass  cover  sufficiently  to  lower  the 
burning  phosphorus  into  the  jar  of  nitro- 
gen. Cover  again  as  quickly  as  possible. 

a.  What  do  you  observe? 

b.  What,  then,  is  the  most  striking  dif- 

ference between  the  effect  of  oxy- 
gen and  nitrogen  on  heated  phos- 
phorus ? 

3.  If  you  are  sure  that  air  has  been  kept  out 

of  the  jar,  see  if  sulphur,  carbon,  or  iron 
will  burn  in  nitrogen. 

a.  What  do  you  conclude? 

b.  Did  the  nitrogen  itself  burn  in  any  of 

the  preceding  experiments? 

c.  Does  nitrogen  make  things  burn? 

d.  What  is  the  advantage  of  having  air 

composed  of  both  oxygen  and  nitro- 
gen? 
C.  Percentage  composition  of  air. 

1.  Pour  the  water  at  the  bottom  of  the  jar 

into  a  cylindrical  graduate.  How  much 
water  is  there?  (This  water  took  the 
place  of  the  oxygen  as  fast  as  the  latter 
was  removed  from  the  air  by  the  burn- 
ing phosphorus.)  What,  therefore,  was 
the  volume  of  oxygen  in  the  air? 

2.  Fill  the  jar  with  water  and  then  pour  it  into 


12  LABORATORY  EXERCI8S8. 

the  cylindrical  graduate.  What  is  the 
volume  of  the  water,  or  in  other  words 
how  much  air  was  in  the  jar  at  first? 
3.  The  water  measured  in  i  above  represents 
the  volume  of  the  oxygen  and  the  water 
in  2  the  whole  volume  of  air  in  the  jar. 
About  what  fractional  part  of  air  is  oxy- 
gen? What  per  cent,  of  oxygen  is  there- 
fore found  in  air?  What  per  cent,  is 
nitrogen? 


4.    STUDY  OF  ATMOSPHERIC  PRESSURE. 

Materials:  Tumbler  of  water,  piece  of  paper,  apparatus  for 
preparing  oxygen,  apparatus  for  preparing  nitrogen.  (See  Figs.  1 
and  2.) 

A.  Fill  a  tumbler  nearly  full  of  water  and  cover  it 

with  a  piece  of  paper,  pressing  it  down  firmly 
upon  the  glass.  Carefully  invert  the  tumbler 
and  then  remove  the  hand  from  beneath  the 
paper. 

a.  What  do  you  observe? 

b.  Slowly  turn  the  glass  until  the  paper 

stands  vertically.     Describe  result. 

c.  Turn  the  glass  upright.     Describe  the 

appearance  of  the  paper. 

d.  (The  air  exerts  in  all  directions  at  the 

level  of  the  sea  a  pressure  equal  to 
about  fifteen  pounds  to  the  square 
inch.)  Keeping  in  mind  this  fact 
explain  the  preceding  experiments. 

B.  In  the  preparation  of  oxygen  explain  why  the 


STVDY  OF  BTDROGfitf.  H 

inverted  bottles  remained  filled  with  water. 
Measure  the  length  and  breadth  of  the  tray  of 
water.  How  many  square  inches  are  there  on 
the  surface  of  the  water?  If  the  pressure  on 
each  square  inch  is  fifteen  pounds,  what  is  the 
pressure  of  the  atmosphere  on  the  whole  sur- 
face? 

C.  When  the  oxygen  was  removed  from  the  jar  in 
the  nitrogen  experiment,  why  did  the  water 
rise?  Invert  a  jar  of  air  and  press  it  down 
into  the  water.  What  is  the  level  of  the  water 
within  the  jar  now?  Explain. 


5.  STUDY  OF  HYDROGEN.     (Dem.) 

Materials  :  Two  small  bottles,  each  fitted  with  a  rubber  stopper 
fn  which  are  two  holes,  thistle-tube,  delivery-tube,  tray  of  water, 
test-tube,  wide-mouth  bottle,  pieces  of  zinc,  diluted  hydrochloric 
acid,  potassium  permanganate  solution. 

A.  Preparation  of  hydrogen. 

i .  Put  some  small  pieces  of  zinc  into  the  bottle 
and  insert  the  stopper.  Through  one 
hole  in  the  stopper  pass  the  thistle-tube 
until  the  lower  end  nearly  touches  the 
bottom  of  the  bottle.  Pass  one  end  of 
the  delivery-tube  through  the  second 
hole  and  let  the  other  end  of  the  tube 
dip  beneath  the  water  in  the  tray.  Pour 
into  the  thistle-tube  dilute  hydrochloric 
acid  until  the  lower  end  of  the  thistle- 
tube  is  covered. 
a.  What  do  you  see  within  the  bottle? 


LABORATORY  EXERCISES. 

(This  is  an  evidence  that  chemical 
action  is  taking  place.) 

b.  Feel  of  the  bottle.     What  is  a  second 

proof  of  chemical  action? 

c.  What  do  you  see  at  the  free  end  of  the 

delivery -tube?  This  gas  is  hydro- 
gen. 

Fill  a  test-tube   with  water  and  invert  it 
over  the  mouth  of  the  delivery-tube. 

a.  What  other  gas  is  collected  in  a  sim- 

ilar way? 

b.  Wrap  the  tube  in  a  towel,  still  hold- 

ing it  upside  down,  and  hold  the 
mouth  near  a  burning  match. 
What  do  you  hear? 


Potassium 
fermanganat 


FIG.  3. 

c.  If  an  explosion  occurs,  fill  the  tube 
with  hydrogen  a  second  time. 
When  the  gas  burns  quietly,  col- 
lect a  bottle  as  you  collected  the 
oxygen,  but  keep  it  upside  down 


STUDY  OF  HYDROGEN.  15 

after  removing  it  from  the  tray  of 
water.     (If  the  hydrogen  does  not 
come    off    in    sufficient    quantity, 
add  some  more  hydrochloric  acid 
to  the  zinc  in  the  bottle.) 
3.  To    obtain    pure    hydrogen,    first    pass    it 
through   a   solution    of   potassium   per- 
manganate in  a  glass  bottle  and  then  col- 
lect it  in  a  tray  of  water.     This  solution 
removes  the  impurities  from  the  hydro- 
gen.    (See  Fig.  3.) 
B.  Properties  of  hydrogen. 

1.  What  are  some  of  the  physical  properties 

of  hydrogen?  Hydrogen  is  the  lightest 
known  substance.  Why,  therefore,  are 
the  bottles  kept  upside  down? 

2.  Carefully  lift  one  of  the  bottles  of  hydrogen 

and  thrust  up  into  the  mouth  a  burning 
splinter  of  wood. 

a.  Does  the  carbon  continue  to  burn? 

b.  What  do  you  notice?    What  is  the 

color  of  the  flame? 

c.  How,  then,  does  hydrogen  differ  from 

oxygen?  from  nitrogen? 

3.  Remembering  that  a  mixture  of  oxygen 

and  hydrogen  may  cause  a  dangerous 
explosion,  collect  a  test-tube  of  hydro- 
gen to  make  sure  that  all  the  oxygen  has 
been  driven  out  of  the  bottle  and  deliv- 
ery-tube. Remove  the  end  of  the  de- 
livery-tube from  the  water  and  attach 
a  piece  of  glass  tubing  that  has  been 


16  LABORATORY  EXERCISES. 

drawn  out  until  the  opening  is  small. 
Stand  away  from  the  tube  and  apply  a 
lighted  match.  (See  Fig.  3.) 

a.  What   do   you   observe?     How   does 

the  color  of  the  flame  differ  from 
that  of  B,  2,  b  above?  (This  dif- 
ference is  due  to  the  heated  glass 
tube.) 

b.  Hold  a  dry  glass  tumbler  over  the 

mouth  of  the  delivery -tube.  What 
do  you  see  on  the  sides  of  the 
glass?  What,  therefore,  is  formed 
when  hydrogen  burns? 

c.  What  was  formed  when  wood  first  be- 

gan to  burn?  What  was  probably 
one  of  the  ingredients  of  wood? 
(See  experiment  J,  C,  2.) 

6.     STUDY  OF  EVAPORATION. 

A.  Pour  a  wine-glass  of  water  into  a  saucer  and 

place  it  near  a  heated  stove  or  radiator.  Ex- 
amine at  the  end  of  several  (6-12)  hours. 
What  do  you  observe? 

B.  Pour  the  same  amount  of  water  into  a  second 

saucer,  put  it  in  a  cool  place,  and  compare 
with  (A)  above  at  the  end  of  several  hours. 

C.  Into  a  third  saucer  put  another  wine-glass  of 

water,  cover  with  a  glass  dish,  and  place  be- 
side (A).  What  do  you  find  on  examining  the 
dishes  at  the  end  of  several  hours?  Explain. 

D.  Fill  the  wine-glass  with  water  and  place  it  beside 


ACID,  ALKALINE,  AND  NEUTRAL  SUBSTANCES.    17 

the  first  and   third    saucers.     Compare    the 
amount  of  evaporation  in  the  three  dishes. 
What  do  you  learn? 
E.  From  the  preceding  experiments: 

1.  Define  evaporation. 

2.  State  three  conditions  that  are  favorable 

for  evaporation. 

3.  Name  three  ways  in  which  evaporation  can 

be  lessened. 


7.  ACID,  ALKALINE,  AND  NEUTRAL 
SUBSTANCES. 

Materials:  Diluted  hydrochloric  acid,  dilute  caustic-soda  solution, 
water;  red  and  blue  litmus  paper;  evaporating-dish,  alcohol  or  gas 
lamp,  glass  stirring-rod. 

A.  Tests  for  acid,  alkaline,  and  neutral  substances. 

1.  Place  a  drop  of  diluted  hydrochloric  acid 

on  blue  litmus  paper.     Result? 

2.  Place  a  drop  of  the   diluted  acid  on  the 

tongue.     What  is  the  taste? 

3.  Put  a  drop  of  dilute  caustic  soda  solution 

(which  is  alkaline)  on  red  litmus  paper. 
Result? 

4.  What  is  the  taste  of  the  caustic  soda  solu- 

tion? How  does  it  feel  when  rubbed 
between  the  thumb  and  forefinger? 

5.  Put  a  drop  of  water  on  red  and  then  on  blue 

litmus  paper.  Water  is  a  neutral  sub- 
stance. How  does  a  neutral  substance 
affect  litmus  paper? 


18  LABORATORY  EXERCISES. 

B.  Neutralization. 

1.  Pour  a  small  amount  of  the  hydrochloric 

acid  into  an  evaporating-dish ;  add  caus- 
tic soda,  drop  by  drop,  stirring  continu- 
ally with  glass  rod,  until  pieces  of  red 
and  blue  litmus  paper  remain  unchanged 
when  dropped  into  the  liquid.  (This 
process  is  called  neutralization.) 

2.  Evaporate  the  liquid  in  the  dish  to  dryness 

over  an  alcohol  or  gas  flame. 

a.  What  is  the  appearance  of  the  solid 

that  is  left? 

b.  What  is  its  taste?     What  substance, 

therefore,   is  made  by  combining 
hydrochloric  acid  and  caustic  soda? 

C.  Summary.     From  the  above  experiments — 

1.  Give  some  characteristics  of  an  acid. 

2.  Give  some  characteristics  of  an  alkali. 
•  3.  How  can  you  tell  a  neutral  substance? 

4.  Define  neutralization. 

D.  Applications. 

1.  Drop  small  pieces  of  red  and  blue  litmus 

paper  into  a  solution  of  each  of  the  fol- 
lowing substances :  soap  of  several  kinds, 
lemon  juice,  ammonia,  cream  of  tartar, 
saliva,  baking  soda,  apple  juice,  sugar, 
milk,  white  of  egg,  and  other  common 
substances. 

2.  Record  your  results  by  arranging  all  the 

substances  you  have  tested  in  a  table 
like  the  following; 


TO  DETERMINE  THE  AMOUNT  OF  WATER  IN  FOODS.    19 


Acid. 


Alkaline. 


Neutral. 


8.  TO  DETERMINE  THE  AMOUNT  OF  WATER 
IN  FOODS.    (Dem.) 

Materials:  Piece  of  lean  beefsteak;  two  potatoes;  weighing  bal- 
ances. 

A.  Percentage  of  water  in  beefsteak. 

1.  Weigh  the  piece  of  meat  and  put  it  aside  in 

a  warm  dry  place;  weigh  the  next  day. 
Continue  the  weighings  each  day  until 
the  figure  remains  constant.  (The  loss 
is  mostly  water.) 

2.  Record  your  results  in  tabular  form  as  fol- 

lows: 


Wt.  of  steak. 

Loss  of  original  wt. 

Per  cent,  of  loss. 

Third  day  

etc. 

B.  Percentage  of  water  in  potatoes. 

i.  Remove  a  thin  layer  of  peel  from  one  of  the 
potatoes;  weigh  each  of  them  and  lay 


20  LABORATORY  EXERCISES. 

aside  in  a  warm  dry  place.     Weigh  each 
day,  and  record  results  for  each  potato 
in  tabular  form  as  above. 
2.  What  is  one  use  of  the  peel  of  potato? 


9.  TO  TEST  FOODS  FOR  STARCH. 

Materials  :  Corn-starch,  grape-sugar,  white  of  egg,  mutton  tallow, 
various  food  materials,  water;  iodine  solution;*  small  butter-plate, 
test-tubes,  glass  jar,  alcohol-lamp. 

A.  Method  of  applying  iodine  test. 

Put  a  small  amount  of  corn-starch  in  a  test- 
tube,  add  water  and  shake  the  mixture. 

1.  Does  the   starch  dissolve?     How  do  you 

know?     (Let  the  mixture  stand.) 

2.  Boil  the  mixture. 

a.  What  change  do  you  notice? 

b.  Has   the   starch   dissolved?      (Place 

some  sugar  and  water  in  another 
test-tube,  boil,  and  compare  with 
the  boiled  starch.) 

3.  Pour  a  little  of  the  starch  paste  into  a  test- 

tube,  add  a  drop  of  iodine,*  shake,  and 
record  result. 

4.  Add  a  few  drops  of  the  starch  mixture  to  a 

large  glassful  of  water ;  stir  in  a  few  drops 
of  iodine.     What  is  the  result? 

*  A  quart  (1000  cc.)  of  iodine  solution  is  made  by  dissolving  in  5 
teaspoonfuls  (40  cc.)  of  water,  one-half  teaspoonful  (4  grams)  of 
potassium  iodide,  and  one-fourth  this  amount  of  iodine  (1  gram). 
This  solution,  when  thoroughly  mixed,  should  be  diluted  to  make 
one  quart  (1000  cc.).  In  a  clean  bottle  this  mixture  will  keep  lit- 
definitely. 


TO   TEST  FOODS  FOR  STARCH.  21 

5.  Pour  a  small  amount  of  iodine  into  a  test- 

tube  of  water.     What  do  you  observe? 

6.  Put  a  small  amount  of  grape-sugar  into  a 

test-tube;  into  a  second  test-tube  some 
white  of  egg  mixed  with  water ;  and  into 
a  third  tube  put  some  mutton  tallow 
(fat).  "Add  a  little  iodine  to  each. 

a.  Do  you  notice  any  change  in  the  color 

of  any  of  the  substances? 

b.  Do  any  of  the  colors  resemble  at  all 

the  change  of  color  resulting  from 
the  addition  of  iodine  to  starch? 

7.  From  the  preceding  experiments  state  how 

you  can  determine  whether  a  substance 
contains  much  starch,  little  starch,  or  no 
starch. 
B.  Application  of  iodine  test  to  various  foods. 

1.  Test  as  many  foods  as  you  can  by  adding 

hot  water  to  a  small  amount  of  each  on 
a  white  butter-dish  or  saucer,  and  then 
applying  iodine  (e.g.,  oatmeal,  flour,  raw 
meat,  egg,  milk,  parsnip,  potato,  onions, 
apples  (both  green  and  ripe),  beans,  rice, 
pepper). 

2.  Tabulate  your  results  in  columns  under  the 

following  heads : 


Much  starch. 

Little  starch. 

No  starch. 

22  LABORATORY  EXERCISES. 


10.    TO  TEST  FOODS  FOR  GRAPE-SUGAR. 

Materials :  Grape-sugar,  corn-starch,  white  of  egg,  mutton  tallow 
raisins,  onions,  grapes,  granulated  sugar,  and  other  foods;  Fehling's 
solution  ;  *  test-tubes,  alcohol-lamp. 

A.  Method  of  applying  Fehling's  test. 

1.  Dissolve   a   small  amount   of  grape -sugar 

(glucose)  in  water  in  a  test-tube. 

a.  What  is  the  difference  in  the  effect  of 

water  on  grape-sugar  and  on  starch  ? 

b.  Add  some  Fehling's  solution  *  and  boil. 

What  changes  do  you  notice? 

2.  Into  the  first  of  three  test-tubes  put  some 

white  of  egg  mixed  with  water;  into  a 
second  tube  some  corn-starch ;  and  int-> 
a  third  tube  some  mutton  tallow  (fat). 
Add  Fehling's  solution  to  each  and  boil, 

a.  Does  any  change  take  place  in  the 

color  of  the  Fehling's  solution? 

b.  Do  any  of  the  colors  resemble  at  all 

*  To  make  a  quart  (1000  cc.)  of  Fehling's  solution  dissolve  3  tea- 
spoonfuls  (34.64  grams)  of  pure  pulverized  copper  sulfate  (blue  vit- 
riol) in  a  little  less  than  a  half -pint  of  water  (200  cc.).  Make  a 
second  solution  by  dissolving  in  a  pint  (500  cc.)  of  water  twelve 
heaping  teaspoonfuls  (150  grams)  of  Rochelle  salt  and  3  (5-inch) 
sticks  of  caustic  soda  (50  grams).  Mix  the  two  solutions  thor- 
oughly, and  dilute  with  enough  water  to  make  a  quart  (1000  cc.). 
Fehling's  solution  does  not  keep  for  any  great  length  of  time,  and 
hence  must  be  made  up  fresh  a  short  time  before  it  is  needed.  It 
is  more  convenient  to  prepare  it  in  small  quantities  from  the  tab- 
lets that  may  be  obtained  of  druggists.  Before  making  any  tests 
boil  a  small  quantity  of  the  Fehling's  solution  in  a  clean  test-tube. 
If  it  retains  its  transparent  blue  color  it  is  ready  for  use;  otherwise 
a  fresh  supply  must  be  prepared. 


TO   TEST  FOODS  FOR  NITROGENOUS  SUBSTANCES.   23 

the  color  of  the  Fehling's  solution 
when  it  was  boiled  with  grape- 
sugar? 

3.  How  can  you  determine,  therefore,  whether 
or  not  grape-sugar  is  present  in  a  given 
food? 
B.  Application  of  Fehling's  test  to  various  foods. 

1 .  Test  as  many  different  kinds  of  foods  as  you 

can,  first  treating  them  with  water,  boil- 
ing in  a  test-tube  and  then  boiling  with 
Fehling's  solution  (e.g.,  onions,  grapes, 
both  ripe  and  unripe,  pears,  granulated 
sugar,  honey,  molasses,  meat,  egg). 

2.  Tabulate  your  results  in  columns  under  the 

following  heads: 


Grape-sugar  present. 

Grape-sugar  absent. 

ii.  TO  TEST  FOODS  FOR  NITROGENOUS 
SUBSTANCES. 

(Nitrogenous  substances  are  also  known  as  proteids  and  albumins. ) 

Materials:  White  of  egg,  corn-starch,  grape-sugar,  mutton  tallow ; 
piece  of  meat,  milk,  peas;  concentrated  nitric  acid  and  ammonia; 
test-tubes,  beaker-glass,  thermometer,  alcohol-lamp. 

A.  Effect  of  heat. 

i .  Pour  a  small  amount  of  the  white  of  an  egg 
into  a  test-tube.     (White  of  egg  is  com- 


24:  LABORATORY  EXERCISES. 

posed  of  nitrogenous  substances.)  Place 
a  chemical  thermometer  in  the  test-tube 
and  hold  the  tube  in  a  beaker-glass  of 
cool  water.  Gradually  heat  the  water, 
stirring  continually  with  the  test-tube. 

a.  What  change  takes  place  in  the  egg 

albumen? 

b.  At  what  temperature  does  this  change 

occur? 

2.  Boil  some  milk  in  a  pan.     What  do  you 

notice?  Heat  several  times  and  see  if 
same  result  follows. 

3.  Cook  a  small  piece  of  meat.     How  does  the 

heat  affect  its  outer  surface?  What  is 
your  conclusion  in  regard  to  the  compo- 
sition of  meat? 

B.  Smell  when  burning. 

1.  Place  a  small  piece  of  lean  meat  on  the  top 

of  a  coal  fire  and  allow  it  to  burn.  Have 
you  ever  noticed  this  smell  before?  If 
so,  what  caused  it? 

2.  In  the  same  way  test  milk,  peas,  or  beans. 

Result? 

C.  Effect  of  nitric  acid  and  ammonia. 

i.  Pour  a  little  concentrated  nitric  acid  on  a 
piece  of  hard-boiled  egg  in  a  test-tube. 

a.  What  do  you  observe? 

b.  Wash  off  the  egg  with  water,  add  a 

little  concentrated  ammonia,   and 
note  result. 

2     Put  into  a  test-tube  some  starch  paste  made 
as  in  9  above;  into  a  second  tube  some 


TO   TEST  FOODS  FOR  NITROGENOUS  SUBSTANCES.  25 

grape-sugar;  and  into  a  third  test-tube 
some  mutton  tallow  (fat).  Add  a  little 
concentrated  nitric  acid  to  each  of  the 
three. 

a.  Do  you  observe  any  change  in  the 

color  of  either  of  these  nutrients? 

b.  Pour  off  the  acid  and  add  a  little  con- 

centrated ammonia.     Is  any  effect 
noticeable  ? 

3.  Test  with  a  drop  of  nitric  acid  the  skin  on 

the  tip  of  one  of  your  fingers. 

a.  What  is  the  result? 

b.  Of  what  material  is  the  human  body 

partly  composed  ? 

4.  Apply  the  nitric  acid  and  ammonia  test  to 

as  many  foods  as  you  can  (e.g.,  gelatin, 
peas,  white  meats,  onions,  fruits). 

5.  Tabulate  your  results  in  columns  under  the 

following  heads : 


Nitrogenous  substances  present. 

Nitrogenous  substances  absent. 

D.  From  the  above  experiments  state  briefly  three 
.ways  of  testing  foods  for  nitrogenous  sub- 
stances. 


26  LABORATORY  EXERCISES. 


12.  TO  TEST  FOODS  FOR  FATS  AND  OILS. 

Materials  :  Ground  flaxseed,  corn-meal,  milk,  egg,  butter,  mutton 
tallow;  ether  or  benzine;  beaker-glass,  funnel,  filter-paper. 

Caution !  Never  handle  benzine  or  ether  near  a  flame  or  a  hot 
stove,  since  the  vapor  of  these  substances  is  very  inflammable. 

A.  Method  of  extracting  oils. 

To  two  or  three  teaspoonfuls  of  the  ground 
flaxseed  add  an  equal  volume  of  ether  or  ben- 
zine ;  stir  the  mixture  and  let  it  stand  for  ten 
or  fifteen  minutes.  Filter  and  place  the  liquid 
aside  in  a  good  draught  of  air  until  the  odor  of 
ether  or  benzine  has  disappeared. 

1.  What  kind  of  substance  have  you  obtained? 

2.  What  'is  its  smell? 

3 .  Why  is  benzine  used  to  remove  grease-spots 

from  clothing? 

4.  In  the  same  way  extract  the  fats  from  milk; 

from  egg ;  from  corn-meal. 

B.  Hold  a  piece  of  butter  or  mutton  tallow  in  a 

spoon  over  the  stove. 

1.  What  is  the  effect  of  heat  on  fats? 

2.  How,  then,  can  you  distinguish  between  a 

piece  of  fat  and  a  piece  of  proteid  ? 

C.  Rub  a  little  of  the  flaxseed  on  paper.     Hold  the 

paper  to  the  light. 

1.  What  effect  does  fat  have  on  the  paper? 

2.  Does  starch,  sugar,  proteid,  or  water  have  a 

similar  effect? 

3.  What,  therefore,  is  a  simple  way  of  proving 

the  presence  of  fat  ? 


ANALYSIS  OF  FLOUR.  2? 


13.  TO  TEST  FOODS  FOR  MINERAL 
SUBSTANCES. 

Materials:  Piece  of  meat,  oatmeal,  egg,  milk;  spoon  or  piece  of 
metal  (platinum  foil  is  best). 

A.  Method  of  testing  for  mineral  matter. 

Place  a  bit  of  dried  meat  on  a  spoon  or  on 
platinum  foil,  and  let  it  burn  on  a  hot  coal  fire 
or  over  a  gas-flame  until  no  further  change 
can  be  brought  about  by  heat. 

1.  What  is  the  appearance  of  the   substance 

which  is  left  behind?     (The  ash  is  the 
mineral  substance.) 

2.  Does  heat  affect  this  residue? 

B.  In  the  same  way  test  oatmeal,  egg,  and  milk. 

What  do  you  learn  in  regard  to  the  presence 
of  mineral  substances  in  these  foods? 


14.  ANALYSIS  OF  FLOUR. 

Materials:  Flour,  water;  concentrated  nitric  acid  and  ammonia, 
iodine,  Fehling's  solution;  cotton  cloth,  test-tubes,  glass  dish,  piece 
of  metal  (platinum  foil  is  best). 

Moisten  some  flour  with  water  until  it  forms  a 
tough,  tenacious  dough;  tie  it  in  a  piece  of  cotton 
cloth,  and  knead  it  in  a  vessel  containing  water.   Set 
aside  the  dish  with  the  water. 
A.  Gluten. 

i.  What  are  some  of  the  characteristics  of  the 
substance  (principally  gluten)  within  the 
cloth?  Draw  it  out  into  threads. 


28  LABORATORY  EXERCISES. 

2 1  Test  it  with  nitric  acid  and  ammonia.  What 
kind  of  nutrient  is  gluten? 

B.  Carbohydrates. 

1.  Test  with  iodine   a  small   amount  of  the 

sediment  in  the  water  which  you  used  at 
the  beginning  of  the  experiment.  What 
part  of  the  flour  was  washed  through 
the  cloth? 

2.  Test  with  nitric  acid  and  ammonia  another 

portion.  Are  nitrogenous  substances 
present? 

3.  Test  a  small  portion  of  the  sticky  mass  in 

the  cloth  with  iodine.  What  is  the  re- 
sult, and  what  is  your  conclusion  ? 

4.  Place  a  little  flour  in  a  test-tube,  add  water 

and  boil ;  add  Fehling's  solution  and  boil 
again.  Is  grape-sugar  present  in  flour? 

C.  Mineral  matter. 

Place  a  small  amount  of  dry  flour  on  a  piece 
of  tin  or  platinum  foil  and  cause  it  to  burn 
over  a  very  hot  flame. 

1.  What  changes  take  place? 

2.  What  is  left  after  the  burning? 

D.  Summary. 

1.  What  nutrients  are  present  in  flour? 

2.  State  how  each  of  these  nutrients  can  be 

separated  from  the  rest. 


STUDY  OF  MILK.  29 


15.    STUDY   OF  MILK. 


Materials :  Pint  of  fresh,  rich  milk ;  nitric  acid  and  ammonia, 
Fehling's  solution,  iodine,  caustic  soda,  osmic  acid,  vinegar;  test- 
tubes,  lactometer,  cloth,  alcohol-lamp. 

A.  Fats. 

Put  the  milk  into  a  clean  glass  dish,  and  al- 
low it  to  stand  over  night. 

1.  What  layers  can  be  distinguished? 

2.  Remove  by  means  of  a  spoon  the  top  layer 

into  a  bottle  or  cup  (No.  i). 

3.  Place  a  drop  of  it  on  unglazed  paper.     Let 

the  paper  dry  for   some   time.     What 
kind  of  nutrient  is  shown  to  be  present 
in  milk? 
Nitrogenous  substances. 

1 .  Boil  the  rest  of  the  milk ;  what  change  is  no- 

ticed? What  kind  of  nutrient  is  affected 
in  this  way  by  heat? 

2.  Remove  the  scum  from  the  milk  and  place 

it  in  a  second  cup  (No.  2).  Test  a  little 
of  it  with  nitric  acid  and  ammonia.  Re- 
sult? 

3.  Add  vinegar  to  the  rest  of  the  milk  and 

strain   through  a  cloth.     What  kind  of 
substance  is  left  in  the  cloth?     Test  it 
with  nitric  acid  and  ammonia.     Result? 
Place  this  substance  in  cup  No.  2. 
Carbohydrates. 

i .   Test  a  small  amount  of  fresh  milk  with  Feh- 


30  LABORATORY  EXERCISES. 

ling's  solution.     Result?     (Milk-sugar  or 
lactose   sometimes   gives   the   test   with 
Fehling's  solution  like  grape-sugar.) 
2.  Test  milk  with  iodine.     Is  starch  present? 

D.  Specific  gravity  of  milk. 

1.  Pour  some  good  rich  milk  into  a  tall  glass 

jar.  Test  it  with  a  lactometer  and  re- 
cord specific  gravity. 

2.  Set  the  milk  aside  to  allow  the  cream  to 

rise.  Remove  the  cream  and  test  the 
skim -milk  with  the  lactometer. 

a.  What  change  in  specific  gravity  do 

you  note? 

b.  Explain  this  change. 

3.  Determine  the  specific  gravity  of  a  second 

portion  of  milk.  Dilute  the  milk  with 
water  and  again  find  specific  gravity. 
(Fresh  unskimmed  milk  usually  has  a 
specific  gravity  of  1028  to  1034.)  How 
can  adulteration  of  milk  be  detected? 

E.  Microscopic  examination  of  milk.     (In  class.) 

1.  Place  a  drop  of  milk  on  a  clean  glass  slide, 

and  cover  with  a  cover-glass.  Examine 
under  the  compound  microscope. 

a.  What  is  the  appearance  of  the  oil- 

globules  ? 

b.  Are  they  all  of  the  same  size?     (The 

fat  in  milk  is  said  to  be  in  a  state  of 
emulsion,  each  tiny  sphere  being 
surrounded  by  a  thin  covering  of 
albumin.) 

2.  Place  a  drop  of  dilute  caustic  soda  at  the 


STUDY  OF  FOOD  CHARTS. 


31 


edge  of  the  cover-glass.     What  is  the  ef- 
fect of  the  soda  on  the  oil -globules  ? 
Prepare  a  second  drop  of  milk  for  examina- 
tion as  directed  above  (i).     Place  a  drop 
of  osmic  acid  solution  at  the  edge  of  the 
cover-glass.     What  is  the  effect  of  the 
osmic  acid  on  the  oil-globules  ? 
Reaction  of  milk  when  tested  with  litmus. 

1 .  Test  some  fresh  milk  with  red  and  blue  lit- 

mus paper.  Is  it  acid,  alkaline,  or  neu- 
tral? 

2.  Set  the  milk  aside  in  a  warm  place  and  al- 

low it  to  sour.  Again  test  it  with  the 
red  and  blue  litmus  paper.  What  is  the 
result?  (The  souring  of  milk  is  caused 
by  the  action  of  certain  micro-organisms 
called  bacteria.  See  study  of  bacteria, 
49.) 


16.  STUDY  OF  FOOD  CHARTS. 


(In  "Foods:  Nutritive  Value  and  Cost,"*  or  in  "  Principles  of  Nu- 
trition and  Nutritive  Value  of  Food."*) 

A.  Composition  of  food  materials. 

(Make  estimates  from  Chart  i,  p.  n,  and 
compare  with  per  cents,  given  in  Table  A,  p. 
27,  in  "  Foods:  Nutritive  Value  and  Cost.") 
i.  Which  kind  of  food  (animal  or  vegetable) 

*  The.se  pamphlets  will  be  furnished  free  by  the  U.  S.  Department 
of  Agriculture,  Washington,  D.  C« 


32  LABORATORY  EXERCISES. 

has  on  the  average  the  larger  per  cent,  of 
proteid  ? 

2.  Which  kind  has  the  larger  per  cent,  of  fat? 

3.  Which  kind  has  the  larger  per  cent,  of  car- 

bohydrates ? 

4.  Note  the  principal  nutrients  present  in  ani- 

mal foods,  and  state  what  use  the  body 
can  make  of  this  class  of  foods. 

5.  In  the  same  way  state  the  principal  uses  of 

vegetable  foods. 

6.  Name  five  animal  foods  that  contain  a  large 

per  cent,  of  material   for   muscle-build- 
ing. 

7.  Name  five  vegetable  foods  that  contain  a 

large  per  cent,  of  material    for  muscle- 
building. 

8.  Name  five  foods  that  could  supply  a  large 

amount  of  heat  for  the  body. 

9.  Suggest    reasons    why    any    of    the    foods 

named  in  answer  to  questions  6,  7,  and 
8  above  would  not  be  the  most  healthful 
foods  for  the  body. 
B.  Pecuniary  economy  of  food. 

(Make  estimates  from  Chart  2,  p.  22,  and 
compare  with  per  cents,  given  in  Table  B,  p. 
27,  in  "  Foods;  Nutritive  Value  and  Cost.") 

1.  Can  larger  amounts  of  animal  food  or  of 

vegetable  food  be  purchased  for  ioc.? 

2.  Suggest  some  reasons  for  the  fact  you  have 

just  stated. 

3.  Which  kind  of  food  material  named  on  the 

chart  is  cheapest?     (That  is,   of  which 


THE  STUDY  OF  THE  MOUTH.  33 

kind  could  you  secure  the  largest  amount 
for  ioc.?) 

4.  Which  kind  of  food  material  is  most  ex- 

pensive ? 

5.  Which  of  the  three  kinds  of  steak  named  on 

the  chart  is  the  most  economical? 

6.  About  what  fractional  part  of  a  pound  of 

each  kind  of  nutrient  is  needed  each  day 
by  an  American  at  moderate  work  ?  (Last 
line  on  p.  22  and  p.  28.) 
Which  food  on  the  chart  comes  nearest  to 
supplying  the  nutrients  in  the  right  pro- 
portions? 

8.  Why  is  it  better,  therefore,  to  eat  a  variety 

of  foods  rather  than  a  single  kind? 

9.  On  p.  10  learn  the  definition  of  (a)  the  most 

healthful  food,  (b)  the  cheapest  food,  (c) 
the  best  food. 


17.    THE  STUDY  OF  THE  MOUTH. 

Take  a  position  with  your  back  toward  a  strong 
light  and  study  your  mouth-cavity  by  means  of  a 
hand-mirror. 
A.  Walls  of  the  mouth-cavity. 

1.  Press    the    forefinger    against    the    upper, 

lower,  and  side  walls  of  the  mouth;  in 
which  of  these  regions  are  the  walls  rigid 
(bone)  ?  in  which  regions  are  they  yield- 
ing (muscle)? 

2.  What  differences  do  you  note  between  the 


LABORATORY  EXERCISES. 


outer  and  inner  coverings  of  the  cheek? 
What  are  the  characteristics  of  mucous 
membrane  (inner  covering)  ? 

3.  Pull  aside  with  the  forefinger  one  corner  of 

the  mouth.  Notice  the  small  elevation 
on  the  inside  of  the  cheek.  Opposite 
what  tooth  does  it  lie?  (The  duct  from 
one  of  the  salivary  glands  opens  on  this 
elevation.) 

4.  Press  the  tongue  down  with  the  forefinger. 

Make  a  drawing  of  the  opening  into  the 
throat 

5.  If  possible,  locate  and  describe  the  tonsils. 
B.  The  teeth. 

1.  Close  the  jaws  and  open  the  lips;  do  the 

front  teeth  of  the  upper  jaw  cover  the 
ends  of  the  lower  teeth  or  vice  versa? 

2.  Are  the  front  teeth  of  the  upper  jaw  larger 

or  smaller  than  those  of  the  lower  jaw? 

3.  Count  your  teeth  and  record  result  in  a 

table  like  the  following : 


Right  half  of 
upper  jaw. 

Left  half  of 
upper  jaw. 

Right  half  of 
lower  jaw 

Left  half  of 
lower  jaw. 

Incisors  
Canines  
Bicuspids  .... 
Molars 

Place  a  piece  of  string  between  the  teeth 
and  describe  motion  of  jaws  in  biting  it 
off .  Describe  the  movements  of  the  j  aws 
in  chewing, 


TO  PREPARE  DIGESTIVE  JUICES.  35 

C.  The  tongue. 

1.  What  is  the  shape  of  the  tongue? 

2.  Where  is  the  tongue  attached? 

3.  What  parts  of  the  walls  of  the  mouth-cavity 

can  be  touched  by  the  tip  of  the  tongue  ? 

4.  What  differences  do  you  note  between  the 

upper  and  lower  surfaces  of  the  tongue? 

D.  The  use  of  the  lips  and  tongue  in  speaking. 

1.  Pronounce  .the  vowels  of  the  alphabet. 

a.  Are  the  lips  closed  or  open? 

b.  Does  the  tip  of  the  tongue  touch  the 

teeth? 

c.  Does  the  tip  of  the  tongue  touch  the 

palate  ? 

d.  What  is  the  shape  of  the  mouth-cavity 

when  you  are  pronouncing  each  of 
these  vowels? 

2.  What  consonants  necessitate  the  closing  of 

the  lips?     (These  consonants  are  called 
labials.) 

3.  What   consonants   require   the   tongue   to 

touch  the  teeth?     (These  are  called  the 
lingual  consonants.) 


18.  TO  PREPARE  DIGESTIVE  JUICES.     (Dem.) 

Materials  .  Cardiac  end  of  pig's  stomach;  pancreas  of  pig;  gall  of 
ox ;  strong  gl  \rcerm,  1%  solution  of  hydrochloric  acid,  1  5%  solution 
of  sodium  carbonate:  solid  pepsin,  pancreatin,  and  ox -gall. 

A.  Preparation  of  pepsin  solution. 

Procure  the  stomach  of  a  pig,  wash  it  out 
with  a  gentle  stream  of  water.     Tear  off  the 


36  LABORATORY  EXERCISES. 

.  mucous  membrane  from  the  cardiac  (cesoph- 
ageal)  end  of  the  stomach.  Dry  the  mem- 
brane between  folds  of  blotting-paper,  and 
mince  it  finely.  Place  in  a  bottle  and  add  5 
times  its  bulk  of  strong  glycerin.  Set  aside 
for  several  days,  stirring  occasionally.  Filter 
through  muslin.  (The  glycerin  dissolves  the 
pepsin.)  The  glycerin  extract  may  be  kept 
almost  indefinitely. 

When  required  for  use*  in  digesting  nitro- 
genous substances,  add  10  times  its  volume  of 
.2%  hydrochloric  acid,  and  filter. 

Instead  of  preparing  the  glycerin  extract  an 
artificial  gastric  juice  may  be  made  by  dissolv- 
ing solid  pepsin  in  water  and  adding  the  hydro- 
chloric acid. 

B.  Preparation  of  pancreatin  solution. 

Leave  the  pancreas  of  a  pig  moistened  with 
water  for  a  day ;  then  mince  it  well  and  add  i  o 
times  its  volume  of  strong  glycerin.  Set  the 
mixture  aside  for  several  days,  stirring  occa- 
sionally. Filter  through  muslin.  (The  gly- 
cerin dissolves  out  the  pancreatin.) 

The  glycerin  extract  acts  on  starch  and  nitro- 
genous substances.  When  required  to  digest 
fats  add  10  volumes  of  1.5$  solution  of  sodium 
carbonate,  shake  and  filter. 

An  artificial  pancreatic  juice  can  be  made 
by  dissolving  solid  pancreatin  in  water  and 
adding  the  sodium  carbonate  solution. 

C.  Preparation  of  bile. 

Procure  the  fresh  gall-bladder  of  an  ox :  wash 


THE  DIGESTION  OF  STARCH. 


37 


ft,  make  a  small  opening  with  a  knife,  and  col- 
lect the  bile  in  a  bottle.  (The  bile  of  herbiv- 
orous animals  is  green  in  color;  human  bile 
when  fresh  is  a  golden-brown  liquid.) 

A  solution  of  solid  ox-gall  in  water  may  be 
used  instead  of  the  contents  of  the  gall-blad- 
der, if  the  latter  cannot  be  easily  obtained. 


19.   THE  DIGESTION  OF  STARCH. 

Materials:  Corn-starch,   saliva,  pancreatin  solution;  test-tubes; 
alcohol-lamp. 

A.  By  saliva. 

Put  a  small  amount  of  corn-starch  in  a  test- 
tube,  add  water  and  boil ;  dilute  the  paste  until 
a  smooth,  thin  mixture  is  formed. 

1.  Pour  into  a  test-tube  a  small  amount  of  this 

starch  mixture,  and  test  with  Fehling's 
solution.  What  is  the  result  and  what 
is  your  conclusion? 

2.  Allow  some  saliva  to  flow  from  the  mouth 

into  a  clean  test-tube ;  *  test  it  with  Feh- 
ling's solution.  What  is  your  inference? 

3.  Pour  some  saliva  into  the  starch  paste  made 

at  the  beginning  of  the  experiment,  shake 
the  mixture  and  warm  gently  for  a  mo- 
ment or  two.     Test  with  Fehling's  solu- 
tion.    Result? 
...  What  is  the  effect  of  saliva  on  boiled  starch? 

*  Saliva  sufficient  for  the  class  may  be  obtained  by  the  teacher  be- 
fore the  exercise. 


38  LABORATORY  EXERCISES, 

5.  Name  several  foods  already  studied  which 

could  be  partially  digested  by  saliva. 

6.  Hold  a  small  amount  of  the  boiled  dilute 

starch  paste  in  the  mouth.  What  is  the 
taste  at  first  ?  Do  you  notice  any  change; 
if  so,  what  change? 

B.  By  pancreatic  juice. 

1.  Dissolve  a  little  pancreatin  in  water.     Test 

a  small  portion  of  it  with  Fehling's  solu- 
tion. What  is  your  conclusion? 

2.  Add  some  pancreatin  solution  to  some  of  the 

starch  paste;  warm  and  test  with  Feh- 
ling's solution.  Result? 

C.  What  digestive  juices  of  the  human  body  act 

upon  starch?     What  change  do  they  cause? 


20.  DIGESTION  OF  MINERAL  SUBSTANCES. 

Materials :  Table-salt,  phosphate   of  lime,   diluted   hydrochloric 
acid;  evaporating-dish,  alcohol-lamp. 

A.  Soluble  salts. 

Put  some  table-salt  into  a  test-tube,  add 
water,  and  shake  well. 

1 .  Does  the  salt  dissolve ?     How  do  you  know? 

2.  In  what  part  of  the  alimentary  canal  may 

salt  become  liquefied,  and  how? 

3.  What  is  meant  by  a  soluble  salt  or  soluble 

mineral  substance? 

B.  Insoluble  salts. 

Put  some  phosphate  of  lime  (one  of  the  con- 


DIGESTION  OF  NITROGENOUS  SUBSTANCES.      39 

stituents  of  milk)  into  a  test-tube,  add  water, 
and  shake  well. 

1.  Does  the  substance  dissolve?     How  do  you 

know? 

2.  Add  a  little  diluted  hydrochloric  acid  and 

shake.     What  change  do  you  observe? 

3.  Evaporate  to  dryness  in  an  evaporating- 

dish  some  of  the  liquid  obtained  in  2. 

a.  What  is  the  appearance  of  the  sub- 

stance which  is  left? 

b.  Will  it  dissolve  in  water? 

c.  Into  what  kind  of  a  salt  has  hydro- 

chloric acid  changed  the  insoluble 
salt? 

4.  (Hydrochloric  acid  is  one  of  the  ingredients 

of  gastric  juice.)  In  what  part  of  the 
alimentary  canal  are  insoluble  salts  di- 
gested, and  how  are  they  digested? 


21.    DIGESTION  OF  NITROGENOUS 
SUBSTANCES.     (Dem.) 

Materials :  Hard-boiled  egg,  pepsin,  pancreatin,  hydrochloric  acid, 
baking-soda;  test-tubes,  labels. 

A.  Action  of  gastric  juice. 
T.  Experiments. 

a.  Thoroughly  mince  a  piece  of  hard- 
boiled  egg  and  place  a  portion  of 
it  in  a  test-tube;  half  nil  the  tube 
with  water.  Label  Test  No.  i, 
minced  egg  +  water. 


4:0  LABORATORY  EXERCISES. 

b.  Place  in  another  test-tube  the  same 

quantity  of  minced  egg  and  water 
as  in  tube  No.  i ;  add  a  little  di- 
lute hydrochloric  acid.  Label  Test 
No.  2,  minced  egg  +  water  +  hydro- 
chloric acid. 

c.  Into  a  third  tube  put  some  minced  egg 

and  water,  and  add  a  small  amount 
of  pepsin.  Label  Test  No.  3, 
minced  egg  -f  water  +  pepsin. 

d.  Place  some  of  the  minced  egg  into  a 

fourth  tube  and  add  all  three  in- 
gredients of  gastric  juice,  namely, 
water,  a  little  hydrochloric  acid, 
and  pepsin.  Label  Test  No.  4, 
minced  egg  +  water  +  hydrochloric 
acid-f-  pepsin. 

e.  Put  a  lump  of  the  hard-boiled  egg  in  a 

fifth  test-tube;  add  water,  hydro- 
chloric acid,  and  pepsin,  as  in  Test 
No.  4.  Label  Test  No.  5,  lump  of 
egg  +  water  +  hydrochloric  acid-H 
pepsin. 

/.  Put  all  five  tubes  in  a  warm  place  (98° 
F.)  and  shake  them  at  frequent  in- 
tervals. Examine  them  at  the  end 
of  a  few  hours  and  at  the  end  of  a 
day  or  two. 
2.  Results  and  conclusions. 

a.  Compare  tests  i,  2,  3,  and  4. 

(i)  In  which  tube  has  the  egg  been 
liquefied  or  digested? 


DIGESTION  OF  NITROGENOUS  SUBSTANCES.      41 

(2)  Are    all    three    ingredients    of 

gastric  juice  necessary  for 
proteid  digestion  or  not? 

(3)  To  what,  therefore,  may  some 

cases  of  indigestion  be  due? 
b.  Compare  tests  4  and  5. 

(1)  In  which  tube  is  digestion  more 

complete  ? 

(2)  What  do  you  learn  in  regard 

to  the  effect  of  thorough 
mastication  of  food? 

(3)  What    provisions    within    the 

stomach,  however,  might 
accomplish  the  digestion 
of  even  poorly  masticated 
food? 

B.  Action  of  pancreatic  juice. 
i.  Experiments. 

a.  Into   a   test-tube   put   some   of   the 

minced  egg;  half  fill  the  tube  with 
water  and  add  pancreatin;  add  to 
the  mixture  a  little  baking-soda  or 
other  alkali.  Label  Test  No.  6, 
minced  egg  +  water  +  pancreatin  + 
alkali. 

b.  In  a  seventh  tube  mix  the  same  quan- 

tity of  minced  egg,  water,  and  pan- 
creatin as  was  used  in  Test  No.  6 ; 
pour  in  a  few  drops  of  hydrochloric 
acid.  Label  Test  No.  7,  minced 
egg  +  water  +  pancreatin  +  acid. 
€.  Put  both  tubes  in  a  warm  place  (98°  F.) 


4:2  LABORATORY  EXERCISES. 

and  shake  them  at  frequent  inter- 
vals.    Examine   them  at  the  end 
of  a  few  hours  and  at  the  end  of 
a  day  or  two. 
2.  Results  and  conclusions. 

a.  In  which   tube  has   digestion  taken 

place? 

b.  Does  pancreatin,   therefore,   perform 

its  digestive  action  by  the  aid  of  an 
alkali  or  of  an  acid? 

22.   DIGESTION  OF  FATS. 

Materials:  Butter, olive-oil,  lard,  white  of  egg;  sodium  carbonate, 
caustic  soda,  hydrochloric  acid;  bile,  pancreatin;  test-tubes,  alcohol- 
lamp,  apparatus-stand;  compound  microscope,  slide,  cover-glass. 

A.  Effect  of  heat  on  fats. 

1.  Put  a  small  piece  of  butter  in  a  spoon  and 

hold  the  spoon  over  a  hot  stove.     What 
change  takes  place  ? 

2.  How,  then,  can  you  distinguish  between  a 

fat  and  a  proteid? 

3.  Hold  a  piece  of  butter  in  your  mouth.   Does 

it  become  liquid  at  the  temperature  of 
the  body? 

B.  Emulsion  of  fats. 

i .  In  a  test-tube  shake  up  a  few  drops  of  olive- 
oil  with  some  caustic  soda  solution. 

a.  What  change  takes  place  in  the  ap- 

pearance of  the  mixture  after  shak- 
ing? (This  mixture  is  called  an 
emulsion.) 

b.  Put  a  drop  of  the  mixture  on  a  glass 


DIGESTION  OF  FAT8.  43 

slide,  cover  with  a  cover-glass,  and 
examine  with  a  compound  micro- 
scope. 

(1)  What  is  the  appearance  of  the 

oil  droplets? 

(2)  Compare  this  appearance  with 

that  seen  in  milk.     (See  ex- 
periment J5  E.) 

2.  In  a  test-tube  shake  some  olive -oil  with  a 

mixture  of  white  of  egg  (albumin)   and 
water. 

a.  What  is  the  appearance  of  the  mix- 

ture? 

b.  Examine  a  drop  under  the  compound 

microscope  as  directed  above. 

3.  Shake  up  a  few  drops  of  the  olive-oil  with 

water  in  a  third  test-tube,  and  let  tube 
stand  for  a  time. 

a.  Compare  the  mixtt-^e  of  oil  and  water 

with  the  '.fixtures  formed  in  i  and 
2  above. 

b.  What  differences  do  you  notice  in  the 

tubes  ? 

4.  Summary. 

a.  Define  an  emulsion. 

b.  State  two  ways  in  which  an  emulsion 

can  be  made. 
C.  Saponification  of  fats. 

i.  Put  a  little  lard  or  olive-oil  in  a  test-tube, 
add  caustic  soda,  and  boil, 
a.  What  is  the  appearance  of  the  mix- 
ture? 


44  LABORATORY  EXERCISES. 

b.  Examine  a  drop  under  the  compound 

microscope  as  directed  above.  Do 
you  see  any  difference  between  this 
mixture  and  that  formed  in  B  i 
above? 

c.  Taste  of  the  mixture.     What  kind  of 

substance  has  been  formed? 
2.  What  is  meant  by  saponification? 

D.  Effect  of  acids  and  alkalis  on  fats. 

1.  Pour  a  little  melted  butter  into  each  of  two 

test-tubes.  Add  to  test-tube  No.  i 
some  diluted  hydrochloric  acid;  to  test- 
tube  No.  2  some  sodium  carbonate  solu- 
tion. Shake  both  tubes  well,  and  allow 
them  to  stand  for  a  few  moments. 

2.  Does  the  butter  remain  mixed  better  with 

an  acid  or  with  an  alkali?  Why,  then, 
dre  fats  not  digested  in  the  stomach? 

E.  The  digestive  action  of  bile. 

1.  Test  with  litmus  paper  the  bile  solution.    Is 

it  acid,  alkaline,  or  neutral? 

2.  Pour  a  little  melted  butter  into  a  test-tube ; 

add  some  of  the  bile  solution.  Does  the 
mixture  resemble  that  formed  in  B  i  or 
B  3  above? 

3.  Examine  a  drop  of  the  mixture  under  the 

compound  microscope.  Does  this  ob- 
servation agree  with  that  made  in  2  just 
above? 

4.  Pour  a  little  thin  starch  paste  into  a  test- 

tube  ;  add  some  bile,  and  after  a  time  test 
the  mixture  with  Fehling's  solution. 
Does  the  bile  act  upon  starch? 


PRINCIPLES  OF  OSMOSIS.  45 

5.  Place  in  another  test-tube  a  little  minced 

white  of  egg ;  add  bile  and  set  aside  for  a 
day  or  two.  Does  the  egg  dissolve? 

6.  State  what  kinds  of  food-stuffs  are  acted 

upon  by  bile,  and  what   kinds  of  food- 
stuffs are  not  acted  upon. 
F.  The  digestive -action  of  pancreatic  juice. 

I-.  Prepare  some  artificial  pancreatic  juice  as 
directed  in  J8  B,  adding  the  sodium  car- 
bonate solution  to  make  it  alkaline. 

2.  Shake  up  a  little  melted  butter  with  some  of 

this  pancreatic  juice.  What  kind  of  a 
mixture  is  formed?  Examine  under  the 
compound  microscope. 

3.  What  kinds  of  food-stuffs  are  digested  by 

the  action  of  pancreatic  juice  (compare 
previous  experiments),  and  what  kind  of 
food-stuffs  are  not  acted  upon? 


23.    PRINCIPLES  OF  OSMOSIS.     (Dem.) 

Materials :  Thistle-tube,  beaker-glass,  grape-sugar,  starch,  white 
of  egg,  Fehling's  solution,  iodine,  nitric  acid,  and  ammonia.  Procure 
the  intestines  of  a  sheep;*  clean  and  inflate  them;  tie  at  intervals, 
and  allow  this  animal  membrane  to  dry. 

A.  Hold  a  thistle -tube  upright,  closing  the  smaller 
end  with  the  thumb.  Into  the  larger  end  pour 
a  thick  solution  of  grape-sugar  (honey  will 
answer)  until  the  liquid  has  half  filled  the  tube 
and  nearly  filled  the  bulb.  Slit  open  one  of 

*  See  foot-note  p.  46. 


46  LABORATORY  EXERCISES. 

the  tubes  of  sheep's  intestine,*  moisten  it,  and 
tie  it  tightly  over  the  larger  end  of  the  thistle- 
tube/  taking  care  that  none  of  the  grape-sugar 
solution  escapes.  Stand  the  thistle-tube  (mem- 
brane down)  in  a  glass  bottle  filled  with  water 
up  to  the  level  of  the  grape-sugar  solution. 
Mark  on  the  bottle  the  level  of  the  two  liquids. 
Connect  a  long  piece  of  glass  tubing  to  the 
smaller  end  of  the  thistle-tube  and  support  it 
in  a  vertical  position.  (The  experiment  can 
be  demonstrated  better  in  a  large  class-room 
if  a  little  red  ink  is  dropped  on  the  top  of  the 
grape-sugar  solution.)  (See  Fig.  4.) 

1.  At  the  end  of  several  hours  notice  the  level 

reached  by  the  liquid  within  the  thistle- 
tube.  Measure  the  difference  between 
the  level  of  the  liquid  within  the  thistle- 
tube  and  the  level  of  the  liquid  in  the 
bottle. 

2.  Remove  with  a  glass-tube  some  of  the  water 

on  the  outside  of  the  thistle -tube  (in  the 
bottle).  Test  it  with  Fehling's  solution. 
What  is  the  result?  How  do  you  ac- 
count for  this  result? 

3.  Which  of  the  two  liquids  (the  water  in  the 

bottle  or  the  grape-sugar  solution  in  the 


*  Parchment  paper  may  be  used  instead  of  the  dried  sheep's  in- 
testine to  cover  the  end  of  the  thistle-tube.  Or  a  membrane  may 
be  obtained  which  will  answer  the  purpose  by  dissolving  the  mineral 
portion  of  an  egg-shell,  leaving  the  lining  membranes  intact;  the 
membrane  may  then  be  tied  to  the  end  of  the  tube 


PRINCIPLES  OF  OSMOSIS. 


4:7 


thistle -tube)  was  the  more  dense  at  the 
beginning  of  the  experiment? 

Has  more  liquid  passed  into  the  thistle-tube 
or  out  from  it  ?  How  do  you  know  ? 

When  two  liquids,  therefore,  of  different 
density  are  separated  by  an  animal  mem- 
brane what  change  tends  to  take  place? 
Is  the  greater  flow  of  liquid  from  the  less 
dense  to  the  more  dense  or  from  the 
more  dense  to  the  less  dense? 


FIG.  4. 

6.  Mark  the  level  of  the  liquid  in  the  thistle- 
tube  at  the  end  of  each  successive  twen- 
ty-four hours.     What  inferences  do  you 
draw? 
B.  Into  a  second  this  tie -tube  carefully  pour  some 

starch-paste,    cover   with   animal   membrane, 


48  LABORATORY  EXERCISES. 

and  invert  in  a  bottle  of  water,  adding  red  ink 
as  in  A  above.  The  experiment  will  be  more 
striking  if  the  level  of  the  liquids  in  the  two 
experiments  is  the  same. 

1.  What  is  the  level  of  the  liquid  within  the 

second  thistle-tube  at  the  end  of  twenty- 
four  hours?  Take  measurements  as  in 
the  preceding  experiments. 

2.  Test  the  water  in  the  bottle  with  iodine. 

What  is  the  result  and  what  do  you  con- 
clude ? 

3.  In  what  respects  are  the  two  experiments 

(A  and  B)  alike?     How  do  they  differ? 

4.  Why,  therefore,  is  it  necessary  that  starch 

be  changed  to  sugar  before  it  can  be  used 

in  the  body? 

C.  Prepare  a  third  thistle- tube  in  the  same  manner 
as  in  A  and  B,  except  that  raw  white  of  egg 
should  be  used  instead  of  sugar  or  starch. 

1.  At  the  end  of  twenty -four  hours  determine 

by  measurement  the  height  of  the  liquid 
in  the  thistle-tube. 

2.  Test  the  water  in  the  bottle  by  boiling  it 

and  then  testing  it  with  nitric  acid  and 
ammonia.  What  is  the  result? 

3.  In  what  respects  are  the  three  experiments 

alike?     How  do  they  differ? 

4.  (Protoplasm  always  contains  water  and  al- 

bumin.) Explain  why  the  protoplasm 
of  cells  can  absorb  liquid  nourishment. 
Can  protoplasm  soak  out  of  cells  ?  Give 
reason. 


DIGESTION  OF  NUTRIENTS. 


49 


D.  Summary. 

1.  From  the  above  experiments  give  a  con- 

cise definition  of  osmosis. 

2.  State  a  law  of  osmosis  that  will  hold  good 

for  all  the  experiments. 

3.  Classify  all  the  substances  you  have  tested 

in  a  table  like  the  following: 


CRYSTALLOIDS. 

(Substances  which  will  readily 
pass  through  an  animal  mem- 
brane.) 


COLLOIDS. 

(Substances  which  will  not  readi- 
ly pass  through  an  animal 
membrane.) 


24.  DIGESTION  OF  NUTRIENTS. 


Kind  of  nutrient. 

In   what    re 
gion    of  ali- 
mentary ca- 
nal is  it  di- 
gested or  dis- 
solved? 

By  what  juice 
is  it  digested 
or  dissolved? 

To  what  sub- 
stance  is   it 
changed? 

In    what   re- 
gion   or  re- 
gions of  ali- 
mentary ca- 
nal is  it  ab- 
sorbed? 

Nitrogenous  food  .  . 
Nitrogenous  food  .  . 
Fat  .                 .... 

Fat  ... 

Starch  

Starch  

Sugar  

Soluble  salt 

Insoluble  salt  
Water  . 

50  LABORATORY  EXERCISES. 


25.    STUDY  OF  BEEF  BLOOD.     (Dem.) 

Materials :  Concentrated  nitric  acid  and  ammonia,  iodine  solution, 
Fehling's  solution;  test-tubes,  alcohol-lamp,  platinum-foil,  bottle 
and  rubber  stopper;  three  bottles  of  blood  prepared  as  follows: 

Bottle  No.  1. — Take  a  bottle  to  the  slaughter-house  and  get  the 
butcher  to  fill  it  with  fresh  blood.  Carefully  set  it  aside  (in  cold 
storage  room  if  possible),  taking  care  not  to  jar  in  the  least  the  con- 
tents. At  the  end  of  several  days  the  solid  clot  should  be  sur- 
rounded by  a  transparent  serum  of  a  pale  straw  color.  Label  the 
bottle  Clotted  Blood. 

Bottle  No.  2. — Get  the  butcher  to  collect  some  blood  in  a  pail  and 
whip  it  rapidly  for  some  time  with  a  brush-broom  or  with  his  hands. 
Fill  bottle  No.  2  with  the  red  liquid  remaining  in  the  pail,  labelling 
it  Defibrinated  Blood. 

Bottle  No.  3. — Collect  the  stringy  substance  clinging  to  the  broom, 
wash  it  with  water  until  it  is  white,  and  place  it  in  bottle  No.  3,  in 
a  4$  solution  of  formalin  *  or  in  80$  alcohol ;  label  it  Blood  Fibrin. 

A.  Study  of  clotted  blood. 

1.  Describe  the  preparation  of  clotted  blood 

(see  Bottle  No.  i  under  Materials  above). 

2.  Pour  off  all  the  liquid  serum  into  another 

bottle  of  the  same  size. 

a.  What  proportion  of  blood  appears  to 

be  serum? 

b.  What  is  the  color  of  the  serum  ? 

3.  The  solid  mass  left  behind  in  Bottle  No.  i 

is  the  blood-clot. 

a.  Hold  the  bottle  in  a  horizontal  posi- 

tion and  compare  the  shape  of  the 
clot  with  that  of  the  bottle. 

b.  What  is  the  size  of  the  clot  compared 

with  the  size  of  the  bottle?     (See 
2,  a  above.) 

*  4%  formalin  is  prepared  by  diluting  1  volume  of  formalin  with 
10  volumes  of  water, 


STUDY  OF  PEEP  BLOOD.  51 

c.  Gently    shake    the    bottle.     Describe 

the  consistency  of  the  clot. 

d.  What  is  its  color?     Is  the  whole  mass 

of  the  same  color? 

4.  Determine  the  composition  of  the  blood- 
serum  by  the  following  experiments : 

a.  Pour  a   small  portion    of  the  serum 

into  a  test-tube  and  heat  gradually 
over  an  alcohol  lamp ;  what  change 
takes  place?  What  kind  of  nutri- 
•  ent  do  you,  therefore,  conclude  to 
be  present? 

b.  Dip  a  piece  of  unglazed  paper  into  the 

blood-serum  and  allow  the  paper 
to  dry.  How  is  the  paper  affected  ? 
What  is  the  second  food-stuff 
found  in  serum? 

c.  Test  a  little  of  the  serum  with  iodine. 

What  is  the  result?  Why  ought 
this  result  to  have  been  expected? 

d.  Pour  into  another  portion  of  the  se- 

rum some  Fehling's  solution  and 
boil.  What  is  the  result?  Did 
you  expect  this  result?  Can  you 
suggest  any  possible  explanation 
of  this  result? 

e.  Put  a  few  drops  of  the  serum  on  a 

piece  of  platinum  foil  and  heat  as 
hot  as  you  can  in  a  gas  flame.  De- 
scribe the  various  changes  that  take 
place  and  explain  each.  What 
kind  of  material  is  left  after  the 


52  LABORATORY  EXERCISES. 

blood  is  completely  burned,  and 
what  does  this  prove  as  to  the 
composition  of  serum? 

/.  Warm  some  blood-serum  in  a  test- 
tube.  What  do  you  find  on  the 
inner  surface  of  the  upper  part  of 
the  tube?  What  ingredient  is 
therefore  present  in  blood  in  large 
quantity? 

g.  From  the  preceding  experiments  name 
all  the  food  materials  you  have 
found  present  in  blood-serum  and 
state  those  that  are  absent. 

B.  Study  of  defibrinated  blood. 

1.  Describe   the   preparation   of   defibrinated 

blood  (see  Bottle  No.  2  under  Materials 
above). 

2.  What   ingredient    of   blood   has   been   re- 

moved?    (See  Bottle  No.  3.) 

3.  Where  is  this  substance  found  in  the  clotted 

blood? 

4.  What,  therefore,  is  the  effect  of  whipping 

blood,  and  why? 

5.  Remove  a  piece  of  blood  fibrin  from  bottle 

No.  3. 

a.  What  is  its  color? 

b.  Pull  it  apart.     Describe  some  of  its 

characteristics.     Is  it  elastic? 

c.  Test  a  piece  of  blood  fibrin  with  nitric 

acid  and  ammonia.     What  do  you 
conclude  as  to  its  composition? 

C.  Change  in  blood  after  mixing  with  oxygen. 


MICROSCOPIC  STUDY  OF  CORPUSCLES.  53- 

.  Pour  a  small  quantity  of  defibrinated  blood 
into  a  glass  bottle.  Describe  its  color. 

.  Stopper  the  bottle  tightly  and  shake  it  vio- 
lently for  a  minute  or  two. 

a.  What  change  has  taken  place  in  the 

appearance  of  the  blood? 

b.  With  what  was  the  blood  mixed  dur- 

ing the  process  of  shaking? 

c.  In  the  human  body  where  does  this 

change  take  place? 


26.  MICROSCOPIC  STUDY  OF  CORPUSCLES. 

(Dem.) 

Materials-  Prepared  slides  of  frog's  blood  and  of  human  blood; 
compound  microscope  (500  diameters) 

A.  Corpuscles  of  frog's  blood. 

1.  How  many  distinct  types  of  solid  bodies 

(corpuscles)   can  you  see  in  the    frog's 
blood? 

2.  Is  there  any  variation  in  the  form  or  size  of 

different  corpuscles  of  the  same  type? 

3.  Draw  two  corpuscles  (differing  as  much  as 

possible)  of  each  type,  much  enlarged, 
labelling  nucleus  and  cell-body. 

B.  Corpuscles  of  human  blood. 

1.  What  is  the  form  of  the  corpuscles  in  hu- 

man blood?     (Examine  several  corpus- 
cles before  deciding.) 

2.  In  what  respects  do  these  corpuscles  differ 

from  those  found  in  frog's  blood? 

i 


54:  LABORATORY  EXERCISES. 


27.    STUDY  OF  THE  BEEF  HEART.      (Dem.) 

Materials:  The  best  material  for  demonstrating  the  structure  of 
the  heart  to  large  classes  is  an  ox  heart.  In  procuring  the  heart 
from  the  butcher  make  sure  that  the  pericardium  is  uninjured  and 
that  the  blood-vessels  are  left  as  long  as  possible 

Cut  around  the  pericardium  just  below  its  attachment  to  the 
upper  part  of  the  heart,  and  lay  the  sac  aside,  so  that  it  may  again 
be  put  around  the  heart.  Attention  should  be  called  to  the  con- 
nective tissue,  of  which  the  pericardium  is  largely  composed,  and  to 
its  smooth,  serous  lining. 

Dissect  away  the  fat  from  the  auricles  in  order  that  their  shape 
may  be  demonstrated.  Make  careful  incisions  into  each  of  the  four 
chambers  in  such  a  way  that  when  the  walls  are  pulled  aside,  the 
following  structures  may  be  demonstrated-  the  openings  from  the 
auricles  to  the  ventricles,  the  mitral  and  tricuspid  valves  that  guard 
these  openings,  the  semilunar  valves  at  the  mouths  of  the  arteries, 
and  the  openings  from  the  veins  into  the  auricles.  Call  attention 
also  to  the  relative  thickness  of  the  walls  in  each  chamber,  and  to 
the  differences  between  arteries  and  veins. 

Many  points  can  be  shown  more  clearly  if  a  second  beef  heart  is 
cut  horizontally  into  three  parts.  The  first  cut  should  be  made 
through  the  two  auricles,  just  above  the  auriculo- ventricular  orifices; 
the  second  should  pass  across  the  two  ventricles,  half-way  between 
the  apex  and  the  openings  from  the  auricles.  It  is  worth  while  to 
make  a  careful  dissection  of  the  two  hearts,  since  they  can  be  pre- 
served in  4$  formalin,*  and  so  used  year  after  year.  If  possible, 
fresh  sheep  hearts,  dissected  as  directed  in  the  preceding  paragraph, 
should  be  supplied  the  students,  so  they  can  verify  the  facts  demon- 
strated by  the  teacher. 

The  following  outline  is  suggested  for  recording  the  principal 
facts  relating  to  the  structure  of  the  heart. 

A.  Using  the  descriptive  terms  anterior  and  pos- 
terior, dorsal  and  ventral,  right  and  left  (with 
reference  to  the  animal),  locate  the  following 

*  4%  formalin  is  prepared  by  diluting  1  volume  of  formalin  with 
10  volumes  of  water. 


STUDY  OF  THE  BEEF  HEART.  55 

structures  in  the  heart,  giving,  when  possible, 
the  number  of  each: 

1.  Auricles.  5.  Mitral  valve. 

2.  Ventricles.  6.  Papillary  muscles. 

3.  Semilunar  valves.      7.  Chordae  tendineae. 

4.  Tricuspid  valve. 

B.  Name  the  chamber  of  the  heart  with  which  each 

of  the  following  blood-vessels  is  connected: 

1.  Aorta.  3.  Pulmonary  veins. 

2.  Pulmonary  artery.     4.  Venae  cavae. 

C.  State  all  the  differences  which  you  note  between — 

1.  Dorsal  and  ventral  surfaces  of  the  heart. 

2.  Anterior  and  posterior  ends  of  the  heart. 

3.  Auricles  and  ventricles. 

4.  Largest  veins  and  largest  arteries. 

5.  Mitral  and  tricuspid  valves. 

6.  Mitral  and  tricuspid  valves  and  semilunar 

valves. 

D.  Enumerate  the  differences  between  the  right  and 

left  sides  of  the  heart. 


56  LABORATORY  EXERCISES. 


28.    CIRCULATION  OF  THE  BLOOD  IN  THE 
TAIL  OF  THE  TADPOLE.     (Dem.) 

Cut  a  hole  a  half-inch  square  near  the  end  of  a  piece  of  thin  board 
three  inches  long  and  one  inch  wide ;  glue  a  thin  cover-glass  over  the 
hole.  Cover  the  rest  of  the  piece  of  wood  with  absorbent  cotton 
soaked  in  water.  Lay  a  live  tadpole  on  the  cotton,  placing  the  tip 
of  the  tail  on  the  cover-glass.  Lay  a  cover-glass  on  top  of  the  tail, 
and  fasten  cheese-cloth  over  the  animal  to  keep  it  in  place.  Keep  a 
plentiful  supply  of  moisture  about  the  animal,  by  allowing  the  end 
of  the  strip  of  cloth  to  dip  into  a  dish  of  water.  Examine  the  tip  of 
the  tail  with  a  compound  microscope  magnifying  about  75  diameters 

.  i.  At  the  highest  focus  note  the  epithelial  cells 
forming  the  outside  layer  of  the  body 
covering.  What  is  their  shape? 

2.  What  is  the  shape  of  the  dark  pigment-cells 

seen  just  beneath  the  epithelial  cells? 

3.  Focus  still  lower  and  study  the  flow  of  the 

blood  in  the  small  capillaries. 

a.  Is  the  current  steady  in  all  the  blood- 

vessels which  you  see? 

b.  Do  the  red  corpuscles  alter  in  shape 

as  they  move  along? 

c.  Can  you  distinguish  any  colorless  cor- 

puscles? 

d.  Draw  a  small  area  of  the  tail,  repre- 

senting the  course  of  the  capilla- 
ries. Indicate  by  arrows  the 
course  of  the  blood  in  each  capil- 
lary. 

NOTE. — If  tadpoles  cannot  be  obtained,  the  web  of  a  frog's  foot 
may  be  examined  after  confining  the  frog  on  a  larger  piece  of  board 
than  that  described  above. 


PULSE  IN  THE  PUPIL'S  OWN  BODY.  57 


29.    PULSE  IN  THE  PUPIL'S  OWN  BODY. 

To  feel  the  pulse  place  the  forefinger  of  the  left 
hand  on  the  radial  artery  of  the  right  hand  at  the 
lower  end  of  the  radius  bone  on  the  palm  side. 
Count  the  number  of  beats  during  a  minute. 

A.  Variations  in  the  pulse-beat. 

1.  Make  out  in  your  note-book  a  statement  of 

your  pulse -rate  taken  under  the  follow- 
ing conditions : 

a.  Before  rising  in  the  morning. 
6.  Just  before  eating  breakfast. 

c.  Just  after  breakfast. 

d.  Just  after  some  violent  exercise. 

2.  What  is  your  conclusion  from  these  obser- 

vations ? 

B.  Find  your  pulse  in  the  following  places  on  your 

body,  locating  each  with  reference  to  the  bones 
of  the  skeleton : 

1.  On  the  side  of  the  head  in  front  of  the  ear. 

Trace  this  artery  as  far  as  possible. 

2.  On  the  back  of  the  head  near  the  top  of  the 

neck. 

3.  On  the  side  of  the  lower  jaw. 

4.  In  the  hollow  back  of  the  knee-joint, 

5.  On  the  ankle. 


58  LABORATORY  EXERCISES. 


30.   STRUCTURE  OF  BONES. 

Materials  (for  each  two  pupils):  A  complete  rib  of  sheep,  care- 
fully separated  from  its  attachment  to  a  vertebra;  a  piece  of  a  rib  of 
beef,  an  inch  long,  sawed  lengthwise  in  halves;  a  leg-bone  of  sheep, 
from  which  meat  has  been  removed;  one-half  leg-bone  like  the  pre- 
ceding, sawed  lengthwise ;  a  piece  of  the  shaft  of  a  leg-bone  of  sheep, 
sawed  cross-wise;  dissecting-needle  and  scalpel.  (After  completing 
the  study  of  the  structure,  lay  aside  the  bones  for  the  next  experi- 
ment.) 

A.  Structure  of  a  rib  (flat  or  tabular  bone) . 

1.  What  is  the  general  form  of  the  bone? 

2.  Try  to  bend  it.     What  do  you  conclude? 

3.  Cut  off  a  thin  slice  of  the  covering  of  the 

enlarged  end  of  the  rib.  Give  some 
characteristics  of  this  cartilage. 

4.  Stick  the  point  of  the  dissecting-needle  into 

the  surface  of  the  bone  where  it  is  free 
from  muscle.  Peel  off  some  of  the  thin 
membrane  of  connective  tissue.  This 
membrane  is  per-i-osf -te-um. 

a.  What  are  some  of  the  characteristics 

of  periosteum?     Try  to  tear  it. 

b.  Where   is   periosteum   found   on   the 

rib?     Where  is  it  wanting? 

5.  Study  the  section  of  the  rib,  pricking  the 

different  parts  with  the  dissecting-needle. 

a.  In   what   respects   does    the   outside 

layer  of  hard  bone  differ  from  the 
spongy  bone  in  the  interior? 

b.  Describe    the    color    of    the    marrow. 

What   does   this  color  suggest  as 


STRUCTURE  OF  BONES.  59 

to  the  presence  of  blood?  Is  the 
marrow  hard  or  soft?  Dig  out  a 
bit  of  it  and  rub  it  on  a  piece  of 
paper.  Hold  the  paper  to  the 
light.  Of  what  nutrient  is  mar- 
row largely  composed? 
B.  Structure  of  a  soup-bone  (long  bone). 

1.  What  is  the  general  form  of  the  bone  ?  How 

does  it  differ  from  a  rib?  How  do  the 
two  heads  at  the  end  of  the  bone  differ 
from  the  shaft  ?  Can  you  suggest  the 
use  of  the  heads? 

2.  What  kind  of  tissue  covers  the  end  of  each 

head?     Suggest  a  reason  for  this. 

3.  Where  is  periosteum  found  and  where  is  it 

absent? 

4.  In  the  longitudinal  section  of  the  long  bone 

distinguish  periosteum,  cartilage,  hard 
bone,  spongy  bone,  and  marrow.  State 
the  region  or  regions  of  the  bone  in 
which  each  is  found. 

5.  Compare  the  cross-section  of  the  shaft  of  a 

long  bone  with  the  cross-section  of  a  rib. 
In  what  respects  do  the  two  resemble 
each  other?     How  do  they  differ? 
C.  Summary. 

1.  Name    all    the    kinds    of  tissue  found   in 

bones. 

2.  Suggest,  as  far  as  you  can,  the  use  of  each. 

3.  Can  you  give  any  reasons  to  explain  why 

bones  are  not  solid  throughout?  (Com- 
pare with  the  frame  of  a  bicycle.) 


60  LABORATORY  EXERCISES. 

D.  Drawings. 

1 .  Represent  in  a  drawing  the  longitudinal  and 

cross-section  of  the  piece  of  rib,  indicat- 
ing diagrammatically  the  different  kinds 
of  tissue. 

2.  In  the  same  way  make  drawings  of  the  lon- 

gitudinal and  cross-sections  of  the  long 
bone. 


31.  COMPOSITION  OF  BONES. 

Materials :  Two  clean  ribs ;  the  two  halves  of  the  soup-bone  used 
in  30;  diluted  hydrochloric  acid  (6  parts  water  to  1  part  acid) ;  weigh- 
ing balances;  a  piece  of  wire. 

A.  Action  of  acid  on  bone. 

Compare  the  two  ribs  as  to  form  and  size; 
place  one  of  them  in  a  bottle  of  diluted  hydro- 
chloric acid.  Allow  the  bone  to  remain  in  the* 
acid  for  a  few  days  and  then  compare  the  two 
ribs  again. 

1 .  Has  the  acid  changed  the  form  of  the  bone  ? 

2.  Has  it  changed  the  size  of  the  bone? 

3.  Try   to   bend   the   two   rib   bones.     What 

change  do  you  observe  to  have  taken 
place  in  the  one  which  has  been  in  the 
acid? 

4.  Pour  some  of  the  liquid  in  which  the  bone 

has  been  soaking  into  an  evaporating- 
dish  and  heat  over  an  alcohol- lamp  or 
over  a  gas-flame  until  the  liquid  has  dis- 
appeared. What  kind  of  substance  is 


COMPOSITION  OF  BONES.  61 

left  in  the  dish?  (This  substance  is  a 
kind  of  mineral  matter  formed  from  the 
mineral  matter  of  the  bone  by  the  action 
of  the  acid.)  See  experiment  20,  B. 
5.  What  properties  of  bone  are  due  to  the 
presence  of  mineral  matter? 

B.  Effect  of  burning  bone. 

Weigh  half  of  the  long  bone  used  in  30.  Tie 
a  piece  of  wire  about  it  and  place  it  in  a  hot 
coal  fire.  Allow  it  to  remain  for  a  half -hour 
and  then  remove  it  carefully  by  means  of  the 
wire. 

1.  Write  in  your  note-book  a  brief  account  of 

all  the  changes  which  you  observed  while 
the  bone  was  in  the  fire. 

2.  Has  the  bone  been  changed  in  form  or  size? 

3.  What  change  can  you  see  in  the  bone? 

4.  What  part  of  the  bone  has  been  most  af- 

fected by  the  fire? 

5.  Try  to  break  the  bone;  what  is  the  use  in 

bone  of  the  substance  which  has  been 
lost? 

6.  Weigh  the  bone  and  determine  what  per 

cent,  of  the  original  bone  remains  as  ash 
(mineral  matter)  and  what  per  cent,  has 
disappeared  (animal  matter). 

C.  Effect  of  boiling  bones  in  water. 

Place  the  other  half  of  the  soup-bone  in  a 
pint  of  water  and  allow  it  to  simmer  on  the 
back  of  the  stove  for  4  to  6  hours.     Strain  the 
liquid  through  a  cloth  and  allow  it  to  cool. 
I.  Describe  the  substance  which  is  obtained. 


LABORATORY  EXERCISES. 

2.  Test  a  small  portion  of  this  "  soup-stock 
for  nutrients.     (Experiments  8-J3.) 


32.  CLASSIFICATION  OF  BONES. 

From  the  articulated  skeleton  make  lists  of— 

1.  Long  bones  (distinguished  by  shaft  and  ar- 

ticular extremities  or  heads). 

2.  Short  bones  (more  or  less  cubical  in  shape). 

3.  Tabular  or  flat  bones  (flat  like  rib  and  with 

no  marrow  cavity). 

4.  Irregular  bones  (all  others). 


33.   STUDY  OF  THE  MUSCLES. 

Definitions. 

1.  The  part  of  the  muscle  which  contracts  is 

the  belly;  the  bands  or  cords  at  the  ends 
are  the  tendons. 

2.  The  end  of  the  muscle,  that  is,  the  tendon, 

which  moves  least  is  called  the  origin;  the 
tendon  which  moves  most,  the  insertion. 

3.  Muscles  which  bend  or  flex  the  limb  are 

called  flexors;  muscles  which  straighten 
or  extend  the  limb,  extensors. 
A.  The  biceps  muscle  (a  flexor  muscle). 

i.  Clasp  the  front  of  the  right  upper  arm  with 
the  left  hand;  draw  up  or  flex  the  right 
forearm  as  far  as  possible.  What 
changes  do  you  notice  in  the  belly  of  the 
muscle  ? 


STUDY  OF  THE  MUSCLEB.  63 

2.  Place  the  tips  of  the  fingers  of  the  left  hand 

at  the  lower  end  of  the  belly  of  the  right 
biceps  muscle  and  the  thumb  at  its  up- 
per end.  Flex  and  extend  the  right  fore- 
arm several  times.  What  change  takes 
place  in  the  length  of  the  muscle  ? 

3.  Enumerate,   therefore,   three  changes  you 

have  found  to  take  place  in  the  belly  of 
a  muscle  when  it  contracts. 

4.  Roll  the  sleeve  above  the  biceps  muscle. 

Let  the  arm  hang  free,  and  with  a  tape- 
measure  get  the  circumference  of  the 
upper  arm  around  the  middle  of  the  belly 
of  the  biceps  muscle.  Flex  the  forearm 
as  strongly  as  you  can  and  then  deter- 
mine the  circumference.  What  is  the 
amount  of  increase  in  size  ? 

5.  With  the  thumb  and  forefinger  of  the  left 

hand  grasp  the  tendon  at  the  lower  end 
of  the  right  biceps  muscle;  rotate  the 
right  forearm.  To  which  of  the  bones 
of  the  forearm,  therefore,  is  the  biceps 
attached?  Point  out  on  the  skeleton 
the  rough  prominence  where  the  tendon 
is  attached  to  this  bone. 

6.  (Dem.)  Demonstrate  on  the  shoulder-blade 

the  point  of  attachment  of  each  of  the 
two  upper  tendons  of  the  biceps. 

7.  Which  tendon  (upper  or  lower)  of  the  bi- 

ceps moves  the  more  when  you  lift  a 
book?  Which  end  is,  therefore,  origin, 
and  which  insertion?  Locate  the  belly 


64:  LABORATORY  EXERCISES. 

of  the  biceps  with  reference  to  the  hu- 
merus. 

B.  The  triceps  muscle  (an  extensor  muscle). 

1 .  Clasp  the  back  of  the  right  upper  arm  with 

the  left  hand;  forcibly  straighten  or  ex- 
tend the  right  forearm  as  much  as  you 
can.  Locate  the  belly  of  the  triceps  with 
reference  to  the  belly  of  the  biceps,  and 
with  reference  to  the  humerus. 

2.  By  flexing  and  extending  the  forearm  de- 

termine the  position  of  the  lower  tendon 
of  the  triceps.  To  which  bone  of  the 
forearm  is  it  attached? 

3.  (Dem.)  Point   out  on  the   shoulder  blade 

and  humerus  the  attachment  of  the  three 
upper  tendons. 

C.  The  flexor  muscles  of  the  fingers  and  of  the  thumb. 

1.  Clasp  the  right  forearm  near  the  elbow; 

clench  the  hand  quickly  and  forcibly. 
Locate  the  belly  of  these  flexor  muscles 
with  reference  to  the  bones  of  the  fore- 
arm. 

2.  Press  the  forefinger  and  thumb  strongly  to- 

gether. What  change  is  noticed  in  the 
thick  mass  of  muscle  at  the  base  of  the 
thumb?  Along  what  bone  does  this 
flexor  muscle  of  the  thumb  lie? 

3.  What  would  be  the  form  of  the  hand  if  the 

flexor  muscles  of  the  fingers  were  located 
in  a  position  corresponding  to  the  flexor 
muscle  of  the  thumb?  What  is  gained 
by  placing  these  muscles  in  the  forearm  ? 


STUDY  OF  THE  MUSCLES.  65 

4.  Measure  the  circumference  of  the  forearm 

when  the  hand  is  open,  and  again  when 
it  is  tightly  closed.  Record  your  results. 
Compare  amount  of  increase  with  fig- 
ures for  biceps. 

5 .  Pull  up  your  sleeve.    Flex  the  fingers  several 

times  i  and  note  the  movements  of  the 
tendons  in  the  wrist.  Along  what  bones 
do  these  tendons  pass? 

D.  The  extensor  muscles  of  the  fingers. 

1.  Straighten  back  the  fingers  as  far  as  pos- 

sible, and  by  feeling  of  the  back  of  the 
forearm  locate  the  belly  of  the  extensor 
muscles  of  the  fingers. 

2.  Move   the  middle   finger   alone.     Describe 

the  movements  of  the  tendons  on  the 
back  of  the  hand.  What  do  you  con- 
clude? 

3.  Flex  the  middle  finger  of  each  hand  until  it 

touches  the  palm  of  the  hand;  place  the 
two  hands  together  (palms  facing)  so 
that  the  tips  of  the  forefingers,  fourth 
fingers,  and  little  fingers  touch,  pressing 
the  backs  of  the  middle  fingers  closely 
together.  Try  to  separate  each  of  the 
pairs  of  fingers,  still  keeping  the  middle 
fingers  pressed  together.  Explain  re- 
sult. (See  2  above.) 

E.  The  muscles  which  move  the  ankle. 

i.  Stand  on  tiptoe  and  locate  in  the  calf  of  the 
leg  the  belly  of  the  extensor  muscles  of 
the  foot  which  cause  this  movement.  To 


66 


LABORATORY  EXERCISES. 


which  bone  is  the  lower  tendon  of  this 
muscle  (tendon  of  Achilles)  attached? 

2.  Determine  the  position  of  the  flexor  muscle 
of  the  foot  by  flexing  the  ankle  as  far  as 
possible.     Which  is  the  larger,  the  flexor 
or  the  extensor?     Why? 
F.  The  jaw-muscles. 

Alternately  close  the  jaws  tightly  together  and 
open  them.  Find  the  muscles  which 
cause  these  movements.  Watch  in  the 
glass  and  describe  the  movements  of 
these  muscles. 

Fill  out  in  your  note-book  a  table  like  the  fol- 
lowing : 


Name  of  muscle. 

Belly  opposite 
what  bone 
or  bones.* 

Origin  at- 
tached to  what 
bone  or  bones. 

Insertion  at- 
tached to  what 
bone  or  bones. 

Biceps 

Triceps.  . 

Flexor  muscles  of  fingers.  .  .  . 
Extensor  muscles  of  fingers  . 
Flexor  muscles  of  foot  

Extensor  muscles  of  foot  

*  Before  deciding  as  to  position  of  origin  and  insertion  be  sure  to 
put  the  forefinger  on  the  middle  of  the  belly  of  each  muscle. 


STUDY  OF  BEEFSTEAK.  67 


34.  STUDY  OF  BEEFSTEAK: 

Materials :  Slices  of  meat  from  the  shank  of  beef  about  an  inch 
thick.  Cut  the  slices  into  blocks  about  a  half -inch  square.  The 
structure  is  seen  more  clearly  if  the  meat  is  allowed  to  dry  in  the  air 
for  a  few  hours.  Dissecting-needles,  slide  and  cover-glass,  com- 
pound microscope  \"  -objective 

A.  Gross  structure  of  muscle. 

1.  Pull  apart  more  or  less  the  small  bundles  of 

which  the  meat  is  composed.  What  is 
their  shape  ?  Are  they  all  the  same  size  ? 

2.  What  is  the  color  of  the  meat?     What  do 

you  infer  as  to  the  presence  or  absence 
of  blood? 

3.  What  are  the  characteristics  of  the  tissue 

(perimysmm)  which  surrounds  and  con- 
nects the  muscle  bundles? 

4.  Can  you  distinguish  any  fat  in  the  piece  of 

meat  you  are  studying?  Make  sure  of 
your  answer  by  rubbing  it  on  a  piece  of 
paper.  If  fat  is  present,  where  is  it  sit- 
uated and  what  are  its  characteristics? 

5.  Is   tendon    (gristle)    present?     If   so,    give 

some  of  its  characteristics. 

6.  Make  a  drawing  of  the  piece  of  muscle  show- 

ing cross  and  longitudinal  sections  ( X  5). 
Label  bundles,  perimysium,  and  fat  and 
tendons  if  present. 

B.  Microscopic  structure  of  muscle. 

Separate  with  dissecting-needles  a  small  por- 
tion of  the  muscle ;  cover  it  with  water  and  tear 


68  LABORATORY  EXERCISES. 

it  apart  with  the  needles  until  you  have  the 
smallest  portion  of  the  bundle  which  you  can 
get.  Place  this  bit  of  muscle  on  a  glass  slide, 
add  a  drop  of  water,  and  tease  it  out  with 
needles;  cover  with  glass  and  examine  under 
the  high  power  of  the  compound  microscope. 

1 .  Of  what  is  the  piece  of  muscle  found  to  con- 

sist? 

2.  Why  is  this  kind  of  muscle  called  striped 

muscle? 

3.  Draw  a  muscle-bundle  as  seen  under  the 

microscope.     Label  fibres,  cross-stripes. 


35.    STRUCTURE  OF  A  JOINT. 

Materials:  Fresh  leg-joint  of  lamb  or  veal;  scalpel. 

A.  Movement  at  the  joint. 

1.  Hold  one  of  the  bones  in  a  fixed  position; 

in  how  many  directions  can  the  other 
bone  be  moved? 

2.  What  prevents  the  joint  from  moving  in 

other  directions? 

B.  Muscles  and  tendons. 

1.  Dissect  away  the  muscle  with  the  scalpel; 

by  what  are  the  muscles  attached  to  the 
bones? 

2.  Try  to  stretch  or  break  these  cords  (ten- 

dons) ;  what  properties  of  tendons  does 
this  demonstrate? 

3.  What  is  the  advantage  of  the  absence  of 

muscle-tissue  over  joints? 


STRUCTURE  OF  A  JOINT.     .  69 

C.  Ligaments. 

1.  What  kind  of  tissue  holds  the  bones  to- 

gether after  the  muscle  is  removed? 

2.  How  is  this  tissue  attached  to  bone  so  as  to 

allow  movement  at  the  joint? 

D.  Joint-cavity. 

1.  Cut  through  the  ligaments  with  a  scalpel  so 

as  to  open  the  joint-cavity;  what  is  the 
appearance  of  the  liquid  within  (synovial 
fluid)  ? 

2.  Suggest  the  use  of  the  synovial  fluid. 

E.  Cartilage. 

1 .  Cut  thin  slices  of  cartilage  from  the  ends  of 

the  bones;  what  are  the  characteristics 
of  cartilage  ? 

2 .  Why  is  cartilage  placed  at  the  ends  of  bones 

where  motion  occurs? 

F.  Bones. 

1.  Describe  the  way  the  bones  fit  together  at 

the  joint. 

2.  Is  twisting  motion  possible  at  this  joint? 

G.  Periosteum. 

Stick  the  point  of  the  scalpel  into  the  sur- 
face of  the  bone  where  all  the  muscle  has  been 
removed.  Peel  off  some  of  the  thin  .mem- 
brane (periosteum). 

1.  What  are  the  characteristics  of  periosteum? 

2.  Where   do   you   find   periosteum   on   long 

bones? 

H.  Make  a  list  of  all  the  structures  found  in  the 
joint,  giving  the  use  of  each. 


70  LABORATORY  EXERCISES. 


36.  STUDY  OF  THE  JOINTS  IN  THE  BODY. 

A.  Ball-and-socket  joints. 

1.  Note  on  the  articulated  skeleton  what  bones 

form  the  joint  at  the  shoulder. 

2.  Point  out  the  bones  forming  the  hip-joint. 

3.  State  the  points  of  resemblance  between 

these  two  joints. 

4.  What  differences  can  you  see  in  the  sockets 

of  the  two  joints?  How  does  the  head  of 
the  femur  differ  from  that  of  the  humerus  ? 

5.  Move  your  right  arm  and  right  leg  at  the 

same  time  from  a  vertical  position  in  an 
arc  sideways  toward  the  right;  state  in 
number  of  degrees  the  greatest  range  of 
motion  possible  at  the  shoulder- joint  and 
at  the  hip- joint. 

6.  In  the  same  way  move  the  arm  and  leg  in  an 

arc  forward  as  far  as  possible ;  backward 
as  far  as  possible.  Compare  the  range  of 
motion  at  each  joint. 

7.  Describe  a  cone  with  the  extended  arm  and 

leg;  twist  the  arm  and  the  leg  at  their 
proximal  ends.  What  kinds  of  move- 
ments are,  therefore,  possible  at  these 
joints  other  than  those  suggested  in  5 
and  6  above? 

8.  Press  the  thumb  on  the  hip-bone  during 

these  movements,  then  on  the  edge  of 
the  shoulder-blade.  Is  either  of  the  two 
girdles  movable?  What  advantages  are 


STUDT  OF  TEE  JOINTS  IN  THE  BODY.  71 

gained  by  the  difference  in  the  structure 
of  these  two  girdles? 

B.  Hinge-joints. 

1 .  Determine  from  the  articulated  skeleton  the 

bones  which  form  the  hinge- joint  at  the 
elbow. 

2.  What  bones  form  the  joint  at  the  knee? 

3.  What  projection  at  the  elbow  occupies  a 

position  corresponding  to  the  knee-cap 
or  patella? 

4.  Move  the  right  forearm  and  the  right  leg  at 

the  same  time;  state  in  which  direction 
(i.e.,  anteriorly  or  posteriorly)  each  is 
bent. 

5.  Hold  the  humerus  and  the  femur  in  a  fixed 

position.  Is  lateral  motion  possible  at 
the  knee  or  elbow- joint  ?  Show  from  the 
articulated  skeleton  the  reason  for  this. 

6.  In  how  many  directions  can  a  hinge- joint 

be  moved?  How,  therefore,  can  you 
distinguish  between  a  ball-and-socket 
and  a  hinge -joint? 

7.  Are  the  joints  between  metacarpals  and 

phalanges  ball-and-socket  or  hinge? 
Why? 

8.  Make  a  list  of  all  the  hinge- joints  in  the 

body,  naming  the  bones  which  form  the 
joint  in  each  case. 

C.  Pivot- joints. 

i.  Place  the  right  forearm  on  the  table  with 
the  palm  of  the  hand  upward.  Without 
lifting  the  elbow  from  the  table  turn  the 


72  LABORATORY  EXERCISES. 

hand  until  the  palm  of  the  hand  rests  on 
the  table. 

a.  Which  of  the  bones  of  the  forearm  has 

crossed  the  other? 

b.  Note  on  the  articulated  skeleton  what 

two  bones  form  this  pivot- joint  at 
the  elbow. 

2.  Study  the  two  top  vertebrae  of  the  spinal 
column;  move  the  vertebrae  on  each 
other.  Describe  the  provisions  that  en- 
able a  person  to  turn  his  head  from  side 
to  side. 
D.  Gliding  joints. 

1.  Count  on  the  articulated  skeleton  the  bones 

forming  the  wrist. 

2.  How  many  form  the  ankle? 

3.  Which  bones  are  the  larger,  those  of  wrist 

or  ankle?  What  advantage  is  gained  in 
each  case? 

4.  Move  your  right  wrist  and  right  ankle  in  as 

many  directions  as  you  can.  At  which 
joint  is  the  greater  range  of  movement 
possible  ? 

5.  Move  your  lower  jaw  in  as  many  directions 

as  you  can. 

a.  Between  what  bones  does  this  move- 

ment take  place? 

b.  To  which  classes  does  this  joint,  there- 

fore, belong? 

6.  Study  the   joints   between   the   vertebras; 

show  how  the  vertebras,  move  on  each 


COMPARATIVE  STUDY  OF  MAMALIAN  SKELETON,    73 

other,  enabling  one  to  bend  the  back  or 
twist  the  spinal  column. 


37.   COMPARATIVE  STUDY  OF  THE  MAMA- 
LIAN SKELETON. 

(At  the  American  Museum  of  Natural  History,  8th  Ave.  and  77th  St.) 

NOTE. — The  skeletons  of  the  lion,  horse,  seal,  musk-ox,  sea  lion, 
and  elephant  are  among  those  best  adapted  for  observation. 

A.  Spinal  column. 

1 .  How  many  vertebrae  are  found  in  the  neck 

(cervical)  region? 

2.  How  many  vertebrae  bear  ribs  (dorsal  ver- 

tebrae) ? 

3.  How  many  vertebrae  in  the  lumbar  region? 

4.  Can  you   determine   how  many  vertebrae 

have  united  to  form  the  sacrum? 

5.  How  many  vertebrae  in  the  tail  (caudal  ver- 

tebrae) ? 

6.  In  what  regions  of   the  spinal  column  are 

curves  noticeable?     How  do  they  differ 
from  the  curves  in  the  human  skeleton? 

7.  Are  spinous  processes  specially  developed 

in  any  region?     (The  head  is  supported 
by  muscles  attached  to  these  processes.) 

B.  Ribs  and  sternum. 

8.  How  many  pairs  of  ribs  has  the  animal? 

9.  How  many  are  attached  to  the  sternum? 
10.  Is  the  sternum  a  single  piece  of  bone?     If 

not,  of  how  many  parts  does  it  seem  to 
consist  ? 


74  LABORATORY  EXERCISES. 

C.  Anterior  appendage. 

11.  Can    you    distinguish    a    shoulder-blade 

(scapula)  ? 

12.  Has  the  animal  a  collar-bone  (clavicle)? 

13.  What  fractional  part  of  the  length  of  the 

anterior  appendage  is  formed  by  the  hu- 
merus? 

14.  What  is  the  relative  size  of  radius  and  ulna? 

15.  Are  radius  and  ulna  anywhere  united  or  is 

it  probable  that  rotation  of  the  radius 
about  the  ulna  is  possible? 

1 6.  Is  the  projection  ("funny-bone '')  on  radius 

or  ulna? 

17.  How  many  wrist-bones  (carpals)  in  the  an- 

terior appendage? 

1 8.  Does  the  animal  walk  on  the  palm  of  the 

hand  or  on  the  tips  of  the  fingers? 

19.  How  many  fingers  (or  toes)  of  anterior  ap- 

pendage does  it  use? 

20.  How  many  bones  are  there  in  each  finger? 

21.  Is  a  thumb  distinguishable? 

22.  What  use  does  the  animal  make  of  the  an- 

terior  appendages?     (Walk,    swim,    fly, 
catch  prey,  burrow,  etc.) 
D.  Posterior  appendage, 

23.  Is  a  knee-cap  (patella)  distinguishable? 

24.  What  is  the  relative  size  of  tibia  and  fibula? 

25.  How  many  ankle-bones  (tarsals)  are  found 

in  the  posterior  appendage? 

26.  How  many  toes  of  the  posterior  appendage 

does  the  animal  use  ? 

27.  Are  the  bones  of  the  appendages  long  and 


ACTION  OP  THE  DIAPHRAGM  AND  THE  LUNGS.   75 

slender  or  short  and  clumsy?     Does  the 
animal,  therefore,  seem  to  be  adapted  for 
swift  or  for  slow  locomotion?     Give  rea- 
sons for  your  answer. 
E.  Teeth. 

28.  What  is  the  dental  formula  (number  of  in- 

cisors, canines,   grinders    in    each    half- 
jaw)  ? 

29.  Did  the  animal  probably  eat  animal  or  vege- 

table food?     Reason  for  answer? 


38.    ACTION  OF  THE  DIAPHRAGM  AND  THE 
LUNGS.     (Dem.) 

Procure  a  bell-jar  with  an  opening  at  the  top  for  a  stopper.  Place 
a  marble  in  the  centre  of  a  sheet  of  rubber,  tie  the  rubber  about  it, 
and  stretch  the  sheet  of  rubber  over  the  larger  end  of  the  bell- jar, 
tying  tightly.  Secure  a  rubber  stopper  (provided  with  two  holes) 
which  will  fit  the  opening  in  the  top  of  the  bell-jar.  Pass  a  thistle- 
tube  through  one  of  the  holes  in  the  rubber  stopper  and  tie  a  toy 
balloon  to  its  lower  end.  Through  the  other  hole  pass  a  glass  tube, 
attaching  to  the  upper  end  a  piece  of  rubber  tubing  closed  with 
a  clamp.  Insert  the  rubber  stopper  in  the  opening  at  the  top  of  the 
bell-jar  with  the  toy  balloon  within  the  jar.  Make  sure  that  all  con- 
nections are  tight,  by  applying  paraffin  to  the  top  surface  of  the  cork. 

The  balloon  represents  a  lung;  the  thistle-tube  to  which  it  is  tied, 
the  larynx  and  windpipe;  while  the  bell-jar  itself  represents  the 
chest-cavity,  and  the  sheet  rubber  the  diaphragm. 

A.  Exhaust  some  of  the  air  from  the  bell-jar  by  ap- 
plying the  mouth  to  the  rubber  tubing,  and 
then  replace  the  clamp. 

i.  Is  the  pressure  of  air  greater  now  within  the 
bell- jar  or  without? 


LABORATORY  EXERCISES. 


2.  What  is  the  effect  on  the  sheet  lubber  of  re- 

moving air  from  within  the  jar?  Explain. 

3.  How  is  the  toy  balloon  affected?     Why? 


FIG.  5. 

B.  Seize  the  marble  tied  into  the  sheet  of  rubber  and 
make  the  latter  move  up  and  down. 

1.  Does  the  air  within  the  bell- jar  have  more 

or  less  room  when  the  rubber  is  pulled 
down? 

2.  Is  the  pressure  within  the  glass  jar  now 


CIRCULATION  OF  AIR  IN  SCHOOLROOM.  77 

greater  or  less  than  when  the  rubber  dia- 
phragm was  pushed  up  into  the  glass 
bell  jar? 

3.  What  is  the  effect  on  the  rubber  balloon  of 
thus  increasing  the  size  of  the  cavity  in 
which  the  balloon  is  hung?     Why? 
C.  Application  to  the  action  of  human  diaphragm 

and  lungs. 

1.  In  what  respects  does  this  model  illustrate 

the  process  of  inhaling  and  exhaling  air 
in  our  own  bodies? 

2.  In  what  respects  does  the  model  fail  to  il- 

lustrate the  process  of  respiration? 

39.    CIRCULATION  OF  AIR  IN  SCHOOLROOM. 
(Dem.) 

Materials:  Concentrated  hydrochloric  acid,  concentrated  ammo- 
nia; evaporating-dishes. 

Pour  into  an  evapora ting-dish  some  concentrated 
hydrochloric  acid ;  into  another  dish  pour  some  con- 
centrated ammonia. 
A.  Bring  the  two  dishes  near  together. 

1.  What  is  the  effect? 

2.  Place  the  two  dishes  near  the  hot-water  or 

steam -pipes.  Describe  the  course  of  the 
fumes. 

3.  Place  the  dishes  near  the  opening  to  a  ven- 

tilator. What  course  do  the  fumes  take  ? 

4.  Draw  a  diagram  of  the  room  and  indicate 

by  arrows  the  course  of  the  moving  air 
as  demonstrated  by  the  fumes. 


78  LABORATORY  EXERCISES. 

B.  Open  a  window,  and  place  the  two  dishes  near  a 
steam-pipe  near  the  window. 

1.  Does  the  moving  air  take  the  same  course 

as  before? 

2.  Does  the  open  window  help  or  retard  the 

ventilation  of  the  room? 

NOTE. — Gunpowder  or  flash-paper  may  be  used  instead  of  the 
acid  and  ammonia. 


40.  INSPIRED  AND  EXPIRED  AIR.     (Dem.) 

Materials :  Thermometer,  bottle  fitted  as  described  in  C  below  J 
lime-water. 

A.  Difference  in  temperature. 

1.  Note  on  a  thermometer  the  temperature  of 

the  air  in  the  room. 

2.  Breathe  for  a  few  seconds  on  the  bulb  of  the 

thermometer.     Note  temperature. 

3.  What  is  the  difference  in  temperature  be- 

tween inspired  and  expired  air? 

B.  Difference  in  amount  of  moisture. 

1 .  Breathe  again  upon  the  polished  bulb  of  the 

thermometer.     Describe  result. 

2.  What  substance  is  thus  shown  to  be  one  of 

the  wastes  excreted  by  the  lungs? 

C.  Differences  in  chemical  composition. 

Secure  a  bottle  fitted  with  a  rubber  stopper 
with  two  holes.  Through  one  hole  in  the  stop- 
per pass  a  glass  tube  (No.  i)  until  it  reaches 
nearly  to  the  bottom  of  the  bottle.  Pass  the 
end  of  another  tube  through  the  other  hole,  al- 


INSPIRED  AND  EXPIRED  AIR. 


79 


lowing  the  tube  to  project  but  a  short  distance 
into  the  bottle ;  attach  a  piece  of  rubber  tubing 
to  the  upper  end  of  this  tube  (No.  2).  Half -fill 
the  bottle  with  clear  lime-water  and  insert  the 
stopper.  (See  Fig.  6.) 

1.  Apply  the  mouth  to  tube  No.  2,  exhausting 

the  .air  from  the  bottle. 
Describe  result. 

2.  Draw      into     the      lungs 

through  the  lime-water 
a  considerable  quantity 
of  air  in  this  way.  Does 
any  change  take  place 
in  the  lime-water? 

3.  Does  inspired  air  therefore 

contain  a  large  amount 
of  carbon  dioxid? 

4.  Apply  the  mouth  to  tube 

No.  i  (which  passes 
below  the  level  of  the 
lime-water).  Expel  the 
air  from  the  lungs 
through  the  lime-water. 
Describe  any  changes 
in  the  lime-water. 

5.  What    is     your    inference 

from  4? 

D.  Name  three  differences  between  inspired  and  ex- 
pired air. 


80  LABORATORY  EXERCISES. 


41.   TEMPERATURE  OF  THE  BODY. 

A.  Place  the  bulb  of  a  chemical  thermometer  be- 

neath the  tongue,  closing  the  lips  over  it. 

1.  To  what  point  does  the  mercury  rise? 

2.  Is  the  temperature  which  you  have  deter- 

mined the  same  as  that  found  by  the 
other  pupils  ? 

3.  Take  your  body  temperature  on  a  cold  day, 

then  on  a  warm  day;  do  you  notice  any 
difference  ? 

4.  Determine  whether  the  body  temperature 

is  the  same  after  violent  exercise  as  it  is 
before. 

B.  Production  of  heat. 

1 .  How  was  heat  produced  in  experiment  \  ? 

2.  How  is  heat  produced  in  your  body? 

3.  Is  light  produced  in  the  human  body  (as  in 


42.   STUDY  OF  THE  SKIN. 

Materials:  Clean  needle;  printer's  or  mimeograph  ink. 

A.  Epidermis. 

i .  Wash  the  hands  thoroughly  in  warm  water, 
then  dry  them;  rub  together  the  palms 
and  fingers  of  both  hands  briskly  for  a 
moment.  What  do  you  see  on  your 
hands  as  the  result?  (This  material  was 
a  part  of  your  non-living  epidermis.) 


STUDY  OF  THE  SKIN.  81 

2.  Run  the  point  of  a  clean  needle  beneath  the 

thin  outer  layer  of  the  skin  on  the  palm 
of  the  hand. 

a.  Does  the  needle  cause  blood  to  flow? 

Is  the  outer  layer  of  skin  (epider- 
mis) supplied  with  blood-vessels? 

b.  Does  the  insertion  of  the  needle  cause 

any  pain?  Can  you  feel  the  point 
of  the  needle  touch  the  skin? 
Would  you  infer  that  nerves  en- 
tered the  epidermis  or  not? 

3.  In  what  regions  of  the  surface  of  the  hand 

is  the  epidermis  thickest?  How  do  you 
know?  In  what  region  is  it  thinnest? 

4.  Press  the  tip  of  the  forefinger  on  a  piece  of 

cloth  covered  with  some  thick  ink  (prin- 
ter's ink  or  mimeograph  ink  is  best),  then 
press  the  finger-tip  on  a  page  in  your  note 
book.  Study  the  impression  made. 

a.  Are   the   black   lines    (made   by   the 

ridges  on  the  finger)  all  of  the  same 
width?  Are  they  all  parallel  to 
one  another? 

b.  In  the  same  way  take  the  impression 

of  the  tips  of  your  other  fingers  and 
of  your  thumb.  In  what  respects 
do  these  various  impressions 
differ? 

c.  Where  else  on  your  hand  can  you  see 

similar  ridges? 

d.  What  other  lines  are  visible  on  the 

palm  of  the  hand? 


82  LABORATORY  EXERCISES. 

B.  Hair. 

1 .  On  what  portions  of  the  hand  is  hair  found  ? 

Where  is  it  wanting? 

2.  Compare  the  hair  on  the  surface  of  your 

hand  with  that  on  the  hand  of  an 
older  person.  What  difference  do  you 
note? 

3.  Do  blood-vessels  run  into  the  hair?     How 

do  you  know? 

4.  Which  part  of  the  hair  is  supplied  with 

nerves?     How  do  you  know? 

C.  Nails. 

1.  What  different  areas  do  you  notice  in  your 

thumb-nail?  How  do  they  differ  in  ap- 
pearance? 

2.  Make  a  drawing  of  your  thumb-nail,  show- 

ing these  different  regions. 

3.  Scrape  off  a  little  of  the  outer  surface  of  the 

nail;  does  this  cause  blood  to  flow?  Are 
nails  supplied  with  blood-vessels? 

D.  Deeper  layers  of  the  skin. 

1.  With  the  thumb  and  forefinger  of  the  right 

hand  grasp  a  portion  of  the  skin  on  the 
back  of  the  left  hand.  Can  you  lift  the 
skin  from  the  muscles  and  tendons  lying 
below  ? 

2.  In  the  same  way  determine  whether  the 

skin  on  the  palm  of  the  hand  and  on  the 
ringers  is  closely  or  loosely  attached  to 
the  underlying  tissue.  What  do  you 
find  to  be  true? 

3.  Determine  the  effect   of  pushing   a    clean 


STUDY  OF  EXCRETION.  83 

needle  point  a  little  distance  into  the 
tissue  lying  beneath  the  epidermis. 

a.  Is   the  tinder  skin  (dermis)  supplied 

with  blood-vessels?     How  do  you 
know? 

b.  Is  the  dermis  supplied  with  nerves? 

How  do  you  know? 
E.  Blood  system  in  the  skin. 

1.  Press  the  finger  of  the  right  hand  on  the 

back  of  the  left  hand;  quickly  remove 
the  finger.  What  difference  do  you  note 
in  the  color  of  the  spot  pressed  and  in  the 
skin  about  this  spot?  Give  an  explana- 
tion of  this  difference. 

2.  From  the  preceding  experiment  can  you  ex- 

plain the  cause  of  sudden  paleness  in  the 
face? 

3.  State  the  difference  in  the  relative  quantity 

of  blood  flowing  through  the  cheek  when 
it  is  flushed  and  when  it  is  pale. 


43.   STUDY  OF  EXCRETION. 

A.  Excretion  from  sensible  perspiration. 

1.  Find  the  exact  weight  of  your  body  imme- 

diately after  breakfast.     Record  the  fig- 
ure. 

2.  Exercise  vigorously  for  several  hours  with- 

out eating  or  drinking. 

3.  Find  again  the  weight  of  the  body.     Do  you 

note  any  difference  in  weight? 


84  LABORATORY  EXERCISES. 

B.  Excretion  from  insensible  perspiration. 

1 .  Lay  the  palm  of  your  hand  (when  your  body 

feels  cool)  on  a  cold  mirror.  What  evi- 
dence do  you  find  of  the  activity  of  the 
skin? 

2.  Lay  the  back  of  your  hand  on  the  mirror. 

a.  Do  you  find  any  difference  between 

the  amount  of  perspiration  from 
the  palm  and  from  the  back  of  the 
hand? 

b.  Study  your  hand  on  a  hot  day  and  an- 

swer the  same  question. 


44.  STUDY  OF  THE  KIDNEY  OF  THE  SHEEP. 

Materials:  Fresh  kidneys  of  sheep  or  pig  in  capsule,  prepared  for 
the  pupil  as  follows :  Slit  the  capsule  on  convex  side  enough  to  allow 
the  kidney  to  be  removed;  cut  the  kidney  from  the  convex  border 
toward  the  hilum  sufficiently  to  open  up  the  cavity  within;  replace 
the  kidney  within  the  capsule;  probe. 

A.  Exterior  of  the  kidney. 

1.  Describe  the  capsule  by  which  the  kidney 

is  surrounded. 

2.  Carefully  remove  the  kidney  from  the  cap- 

sule, taking  care  not  to  tear  the  latter. 
Where  is  the  capsule  attached  to  the  kid- 
ney? 

3.  What  is  the  shape  of  the  kidney? 

4.  What  is  the  color  of  the  kidney?     Why? 

5.  How  many  tubes  can  you  find  connected 

with  this  organ?  Can  you  suggest  the 
use  of  any  of  these  tubes?  (The  depres- 


STUDY  of  THE  KIDNEY  OF  TEE  SHEEP.      85 

sion  in  the  kidney  to  which  the  tubes  pass 
is  called  the  hilum.) 
B.  Gross  structure  of  the  kidney. 

1.  Pull  apart  the  halves  of  the  kidney  suffi- 

ciently to  look  within. 

2.  What  is  the  shape  of  the  cavity  near  the 

hilum  '(sinus  of  the  kidney)? 

3.  By  means  of  a  probe  locate  the  tube  (ureter) 

which  passes  out  from  this  cavity. 

4.  The  layer  on  the  outside  of  the  kidney  sec- 

tion is  called  the  cortical  layer. 

a.  Does  this  layer  anywhere  reach  down 

to  the  sinus? 

b.  What  characteristics  distinguish  the 

cortical  layer  from  the  rest  of  the 
solid  portion  of  the  kidney? 
5-  The  bodies  which  form  the  medullary  por- 
tion of  the  kidney  within  the  cortical 
layer  are  called  the  pyramids  of  Malpighi. 

a.  Why  is  the  name  pyramid  given  to 

them? 

b.  Do  these  pyramids  project  into  the 

sinus  of  the  kidney? 

c.  Press  one  of  the  pyramids  of  Malpighi. 

Can  you  see  any  substance  ooze 
out? 


86 


LABORATORY  EXERCISES. 


45.    SENSATION  OF  TOUCH. 

Materials:  Pen  and  ink,  pin,  ruler,  pair  of  scissors. 

A.  Blindfold  a  person,  touch  lightly  some  portion  of 
his  body  with  a  pen  dipped  in  ink,  and  ask 
him  to  point  out  with  a  pin  the  point  touched, 
as  soon  as  you  have  removed  the  pen. 

1.  Measure  the  distance  with  a  rular  between 

the  ink-dot  and  the  point  touched  with 
the  pin.  Record  result  as  directed  be- 
low in  4. 

2.  Try  the  experiment  several  times  on  the 

same  region  of  the  body.  Do  the  results 
agree  ? 

3.  Try  the  experiment  on  different  parts  of  the 

body. 

4.  Record  results  in  tabular  form  as  follows: 


Part  of  body  experimented  upon. 

Distance  between  points. 

1st  trial. 

2d  trial. 

3d  trial. 

B.  Apply  lightly  the  points  of  a  pair  of  scissors  (sep- 
arated about  a  quarter  of  an  inch)  to  the  palm 
of  your  hand. 

1.  Can  the  points  be  felt  as  two,  or  do  they  feel 

as  one  ? 

2.  Separate  the  points  of  the  scissors  a  little 

more  than  a  quarter  of  an  inch,  and  ap- 


SENSATION  OF  TOUCH.  87 

ply  again.  At  what  distance  apart  can 
the  points  be  felt  as  two? 

In  the  same  way  determine  at  what  dis- 
tance apart  the  points  can  be  felt  as  two 
on  the  tip  of  the  middle  finger,  on  the  tip 
of  the  tongue,  on  the  back  of  the  neck, 
on  the  back  of  the  hand. 

Record  your  results  in  tabular  form  as  fol- 
lows, placing  the  smallest  distance  first, 
and  arranging  the  distances  in  order  from 
smallest  to  greatest. 


Part  of  body  experimented  upon. 

Distance  between  points. 

5.  Apply  the  points  of  the  scissors  at  the  up- 
per part  of  the  arm,  near  the  elbow,  at 
the  wrist,  and  on  the  palm,  noting  at 
what  distance  apart  the  points  are  felt 
as  two. 

a.  Is  the  distance  greater  as  you  ap- 

proach the  shoulder  or  as  you  near 
the  hand? 

b.  Does  it  make  any  difference  whether 

the  points  are  applied  in  transverse 
or  in  longitudinal  axis  of  the  arm? 
C.  Cross  the  middle  finger  of  the  hand  over  the  fore- 
finger, and  rub  the  tips  of  these  two  fingers 
against  the  point  of  your  nose  at  the  same 


88  LABORATORY  EXERCISES. 

time.     What  impression  do  you  receive  in  re- 
gard to  your  nose? 


46.    SENSATIONS  OF  TASTE  AND  SMELL. 

Materials:  Potato,  onion,  apple,  spices,  flavoring  extracts,  sugar, 
salt,  mustard,  quinine  solution,  vinegar. 

A.  Flavors  of  substances. 

1.  Secure  a  bit  of  potato,  a  bit  of  onion,  and  a 

bit  of  apple;  close  your  eyes  and  hold 
your  nose  tightly ;  place  each  of  the  three 
in  your  mouth  successively.  Can  you 
distinguish  by  taste  alone  one  piece  from 
the  others? 

2.  Keeping  the  eyes  closed,  repeat  the  experi- 

ment without  holding  the  nose. 

a.  Can  the  foods  be  distinguished  now? 

b.  What  do  these  experiments  teach  you 

in  regard  to  the  real  nature  of  what 
is  commonly  thought  to  be  the 
taste  of  certain  foods? 

c.  Why  are  many  foods  tasteless  to  a  per- 

son with  a  cold  in  the  head? 

d.  What  method  of  taking  disagreeable 

medicines  is  suggested  by  these  ex- 
periments ? 

3.  Close  your  eyes  and  hold  your  nose;  experi- 

ment with  spices,  sugar,  salt,  mustard, 
quinine  solution,  vinegar,  peppermint, 
vanilla,  etc.  Record  your  results  as  fol- 
lows: 


SENSATIONS  OF  TASTE  AND  SMELL.  89 


Substances  distinguished  by 
taste  alone. 

Substances  distinguished  by 
taste  and  smell. 

• 

B.  Wipe  the  tongue  dry  and  place  upon  it  a  bit  of 

sugar. 

1.  Can  the  sugar  be  tasted? 

2.  To  what  condition  must  foods  be  brought 

in  order  to  be  tasted? 

3.  What  use  of  the  saliva  in  the  mouth  does 

this  suggest? 

4.  Give  a  reason  which  may  explain  why  sand 

is  tasteless? 

C.  Localization  of  taste  sensations  on  the  tongue. 

1 .  Place  a  bit  of  sugar  on  the  tip  of  the  tongue ; 

another  bit  on  the  back  of  the  tongue. 

a.  In  which  case  is  the  sweet  taste  more 

distinct  ? 

b.  Determine  whether  sweet  substances 

are  tasted  more  distinctly  along  the 
middle  of  the  tongue  or  at  the  edge. 

2.  By  using  a  bit  of  salt  determine  in  the  same 

way  what  region  of  the  tongue  is  most 
affected  by  saline  substances. 

3.  Prepare  a  strong  solution  of  quinine  by  dis- 

solving 10  grains  sulphate  of  quinine  in 
i  oz.  water  by  the  aid  of  5  drops  sul- 
phuric acid.  Determine  what  portion 
of  the  tongue  is  most  sensitive  to  bitter 
substances;  the  portion  which  is  least 
sensitive. 


90  LABORATORY  EXERCISES. 

4.  Test  the  various  portions  of  the  tongue  with 

vinegar. 

5.  Record  your  results  as  follows: 


Kind  of  substance. 

Part  most  affected. 

Part  least  affected. 

Sweet 

Sour  . 

Bitter 

Salt  . 

47.   STUDY  OF  BRAIN  OF  SHEEP. 

Materials :  Sheep  heads  can  be  obtained  from  any  butcher,  and 
the  brain  may  be  carefully  removed  in  the  following  way:  With  a 
small  saw  make  two  cuts  along  the  top  of  the  skull,  each  about 
three-quarters  of  an  inch  from  the  mid-line  of  the  head,  care  being 
taken  not  to  cut  into  the  brain.  The  saw-cuts  should  extend  from 
front  of  the  eye-sockets  back  to  the  openings  into  the  ears.  Con- 
nect these  longitudinal  cuts  by  sawing  across  the  skull  in  the  regions 
just  indicated.  In  this  way  a  rectangular  piece  of  bone  is  loosened 
which  can  be  pried  off  by  the  use  of  a  chisel.  The  cerebral  hemi- 
spheres of  the  brain,  enveloped  in  tough  dura  mater,  are  thus  ex- 
posed. The  bony  top  of  the  skull  should  be  preserved  in  4%  solu- 
tion of  formalin  (one  volume  formalin  to  ten  volumes  of  water). 

Continue  the  side  cuts  backward  through  the  hard  bony  pro- 
cesses by  which  the  skull  was  attached  to  the  spinal  column,  and 
with  a  chisel  pry  off  the  rest  of  the  top  and  back  wall  of  the  cranium. 
Beneath  it  lie  the  cerebellum,  the  medulla,  and  the  beginning  of  the 
spinal  cord. 

To  remove  the  brain  from  the  skull  the  head  should  be  supported 
with  the  tip  of  the  skull  downward.  By  means  of  forceps  take  hold 
of  the  dura  mater  on  the  ventral  surface  of  the  spinal  cord  and  care- 
fully pull  it  away  from  the  base  of  the  cranium.  With  dissecting 
scissors  or  with  the  point  of  a  scalpel  cut  off  the  various  nerves, 
leaving  as  much  as  possible  of  each  nerve  attached  to  the  brain.  If 
the  opening  in  the  roof  of  the  skull  is  not  large  enough  to  allow  the 
brain  to  be  taken  out  easily,  the  sides  can  be  cut  away  with  bone 
forceps. 


STUDY  OF  BRAIN  OF  SHEEP.  91 

If  the  work  has  been  carefully  done,  when  all  the  nerves  are  cut, 
the  uninjured  brain  comes  out  of  the  skull  completely  enclosed  in 
its  membrane  of  dura  mater.  This  connective  tissue-sac  should 
then  be  cut  along  the  mid-line  of  the  dorsal  surface,  removed  from 
the  brain,  and  placed  in  4.%  formalin  solution.  The  brains,  as  fast 
as  they  are  removed,  should  be  put  in  a  shallow  dish,  the  bottom 
of  which  is  covered  with  a  soft  layer  of  cotton,  and  over  them  should 
be  poured  a  4£  solution  of  formalin.  When  the  brains  are  '  once 
hardened  in  this  way  they  can  be  kept  in  alcohol  and  used  year  after 
year. 

To  show  the  internal  structure  of  the  brain  a  horizontal  cut  should 
be  made  about  half  an  inch  from  the  lower  surface  of  the  brain 
through  one  of  the  cerebral  hemispheres  and  through  half  of  the 
cerebeflum.  By  making  a  vertical  cut  also,  along  the  ventral  sur- 
face, at  one  side  of  the  median  line  the  lower  third  of  one-half  of  the 
brain  is  removed,  and  the  disposition  of  the  gray  and  white  matter 
within  the  brain  is  shown. 

Each  two  pupils  should  be  supplied  with  a  hardened  brain  pre- 
pared as  described,  a  piece  of,  or,  if  possible,  a  whole  dura  mater,  a 
rectangular  piece  of  bone  from  the  top  of  the  skull  with  skin  and 
wool  attached,  a  dissecting  needle. 

A.  Protection  of  brain. 

1 .  What  kind  of  outer  covering  has  the  sheep  ? 

How  does  it  protect  the  brain? 

2.  Examine  the  piece  of  bone  which  was  re- 

moved from  the  top  of  the  skull.  What 
layers  can  you  distinguish?  Why  is  this 
arrangement  of  bone-tissue  of  great  ad- 
vantage as  a  means  of  protection? 

3.  What  are  the  characteristics  of  the  dura 

mater  (the  sac  covering  the  brain)  ?  Try 
to  tear  it. 

4.  By  means  of  a  dissecting  needle  lift  from 

the  surface  of  a  portion  of  the  brain  a 
thin  covering  called  the  pia  mater.  De- 
scribe it.  Does  it  cover  all  parts  of  the 


92  LABORATORY  EXERCISES. 

brain?  Does  the  pia  mater  have  any 
blood-vessels? 

B.  Fore-brain. 

1.  Describe  the  form  of  the  two  large  masses 

(the  cerebral  hemispheres)  that  consti- 
tute the  principal  portion  of  the  fore- 
brain. 

2.  Where   are   the   cerebral   hemispheres    at- 

tached to  each  other?  (The  groove  be- 
tween them  is  called  the  longitudinal  fis- 
sure.) 

3.  What  is  the  appearance  of  the  dorsal  sur- 

face of  the  fore-brain?  (The  elevations 
are  called  convolutions,  the  grooves  be- 
tween them,  fissures.) 

4.  Near  the   anterior  end  of  the  ventral  sur- 

face of  the  brain  notice  two  small  masses. 
(These  are  the  olfactory  lobes,  which 
connect  with  the  nose  region.)  Describe 
their  form. 

5.  Moisten  the  section  made  in  the  lower  por- 

tion of  one  of  the  cerebral  hemispheres 
and  examine  it.  Distinguish  gray  and 
white  matter.  Where  is  gray  matter 
found  and  where  is  the  white  matter? 

6.  Note  the  cavity  in  the  hemispheres.     What 

is  its  shape  and  size? 

C.  Hind-brain. 

i.  What  is  the  form  of  the  enlargement  (the 
cerebellum)  on  the  dorsal  surface  of  the 
brain  posterior  to  the  cerebral  hemi- 
spheres? 


STUDY  OF  BRAIN  OF  SHEEP.        93 

2.  Is  it  divided  into  two  parts  like  the  fore- 

brain  ? 

3.  What  is  the  appearance  of  its  outer  surface? 

(Compare  with  the  surface  of  the  cerebral 
hemispheres.) 

4.  In  the  section  of  the  cerebellum  describe 

the  distribution  of  gray  and  white  mat- 
ter. 

5.  On  the  ventral  surface  of  the  hind-brain, 

just  beneath  the  cerebellum,  note  a  band 
of  white  matter  (the  pons  =  bridge)  con- 
necting the  lateral  portions  of  the  cere- 
bellum. Does  the  pons,  therefore,  run 
crosswise  or  lengthwise  of  the  brain? 

6.  The  rest  of  the  hind-brain  is  called  the  me- 

dulla (or  medulla  oblongata) .  Name  and 
locate,  now,  each  of  the  three  regions  of 
the  hind-brain. 

7.  The  portion  of  the  nervous  system  which 

forms  a  posterior  continuation  of  the 
medulla  is  the  spinal  cord.  What  is  the 
general  shape  of  the  cord?  Describe  its 
cross  section.  Can  you  distinguish  gray 
and  white  matter?  If  so,  locate  each. 
D.  Mid-brain. 

i.  Carefully  bend  the  brain  near  the  middle 
in  such  a  way  as  to  enable  you  to  look 
down  between  the  cerebral  hemispheres 
and  the  cerebellum.  This  connecting 
isthmus  is  the  mid -brain.  Describe  its 
position  with  reference  to  fore-  and  hind- 
brain. 


94  LABORATORY  EXERCISES. 

2.  How  many  elevations  can  you  distinguish 
on  the  dorsal  surface  of  the  mid-brain? 
'(These  are  the  optic  lobes  which  connect 
with  the  eyes.) 
E.  Cranial  nerves  (Dem.). 

From  what  region  of  the  brain  do  each  of  the 
following  pairs  of  nerves  originate  and  what  is 
their  distribution? 

1.  First  pair  or  olfactory. 

2.  Second  pair  or    optic.     (Note  crossing  of 

these  nerves  on  ventral  surface  of  brain.) 

3.  Third,  fourth,  and  sixth  pairs. 

4.  Fifth  and  seventh  pairs. 
4.  Eighth  pair  or  auditory. 

6.  Ninth,  tenth,  eleventh,  and  twelfth  pairs. 

48.   STUDY  OF  YEAST. 

Materials  for  home  work:  Compressed  yeast,  molasses;  two  pint 
bottles,  small  bottle,  tin  cup;  refrigerator;  stove;  thermometer. 

Materials  for  class  demonstrations:  (A,  9,  10,  D);  Flask,  rubber 
cork  (two  holes);  U-tube,  test-tube;  chemical  thermometer;  glass 
and  rubber  tubing;  water-bath;  condenser;  compound  microscope 
(500  diameters),  slide;  cover-glass;  lime-water,  eosin  or  methyl 
violet. 

A.  Study  of  the  growth  of  yeast. 

Mix  about  an  eighth  of  a  cake  of  compressed 
yeast  in  a  tablespoonful  of  water  and  stir  until 
a  smooth  thin  mixture  is  formed.  Add  this  to 
about  a  half -pint  of  water  in  which  a  table- 
spoonful  of  molasses  has  been  dissolved.  Place 
this  mixture  in  a  wide -mouthed  bottle  which 
holds  about  a  pint;  stopper  very  loosely. 


STUDY  OF  YEAST.  95 

1.  State  in  your  note-book  the  color  of  the 

mixture.     Does  it  appear  clear  or  cloudy  ? 

2.  What  is  the  smell  and  taste  of  the  mixture? 

3.  Place  the  liquid  where  the  temperature  is 

70°  to  90°  F.  Determine  the  exact  tem- 
perature by  the  use  of  a  thermometer, 
and  record  it. 

4.  At  the  end  of  several  hours  examine  the  liq- 

uid. What  evidence  is  there  that  the 
yeast  is  ' '  working ' '  ? 

5.  At  the  end  of  12  hours  smell  the  mixture  of 

molasses  and  yeast  remaining  in  your 
large  bottle.  How  does  it  differ  from 
that  observed  in  2? 

6.  Taste  of  the  liquid  at  the  same  time.     Com- 

pare with  result  obtained  in  2. 

7.  What  differences  do  you  note  in  the  color 

or  in  the  general  appearance  of  the  mix- 
ture since  the  experiment  was  begun? 
(Compare  with  observations  in  i.) 

8.  Determine  the  effect  of  temperature  on  the 

working  of  yeast  in  the  following  man- 
ner: 

a.  Shake  up  the  mixture  when  it  is  work- 
ing well,  and  pour  some  off  into  a 
small  bottle;  immerse  the  latter 
up  to  its  neck  in  ice-water  for  an 
hour,  or  place  it  in  a  refrigerator. 

(1)  What  is  the  effect  on  the  ac- 

tivity previously  noticed  in 
the  liquid? 

(2)  Warm  the  liquid  again  to  the 


96  LABORATORY  EXERCISES. 

temperature  of  the  room  and 
record  result. 

(3)  (Yeast  is  a  plant.)  Has  it  been 
killed  by  the  cold?  Give 
reason  for  your  answer. 

b.  Pour  some  more  of  the  working  yeast 

mixture  into  a  tin  cup,  place  it  on 
the  stove  and  boil  it.  Allow  the 
mixture  to  cool  to  the  tempera- 
ture of  the  room,  and  turn  it  into 
a  small  bottle. 

(1)  What  effect  does  boiling  have 

on  the  activity  of  the  yeast  ? 

(2)  Keep  the  mixture  for  a  day  or 

two.     Was   the   yeast  killed 
by  the  heat? 

c.  Summary. 

(1)  What  temperature  do  you  find 

to  be  most  favorable  for  the 
growth  of  yeast? 

(2)  What  is  the  effect  of  extreme 
.  cold? 

(3)  What  is  the  effect  of  a  high  de- 

gree of  heat  ? 

9.  (Dem.)  Nearly  fill  a  bottle  with  a  yeast 
mixture  which  is  working  well.  Insert 
a  rubber  cork  in  the  mouth  of  the  bottle 
through  which  passes  one  arm  of  a  U- 
tube.  Half-fill  a  test-tube  with  lime- 
water.  Allow  the  free  end  of  the  U-tube 
to  dip  below  the  surface  of  the  lime- 
water.  Be  sure  all  the  connections  are 


STUDY  OF  JEAST. 


97 


in  a 


tight.     Set    the    apparatus   aside 
warm  place  for  a  few  hours. 

a.  What  change  has  taken  place  in  the 

lime-water  ? 

b.  What  kind  of  gas  is  produced  by  the 

growth  of  yeast? 

io.  (Dem.)  Pour  into  another  flask  some  of  the 
yeast  mixture  which  has  been  working 


FIG.  7. 

for  some  time.  Procure  a  rubber  stop- 
per with  two  holes.  Through  one  hole 
pass  the  bulb  of  a  chemical  thermometer 
so  that  it  reaches  half-way  down  to  the 
bottom  of  the  flask.  Through  the  other 


98  LABORATORY  EXERCISES. 

hole  pass  a  glass  tube,  allowing  it  to  pro- 
ject just  inside  the  flask.  Connect  this 
glass  tube  with  rubber  tubing  to  a  con- 
denser (used  in  distillation).  Place  the 
flask  over  a  water-bath,  and  keep  the 
temperature  at  the  point  where  the  ther- 
mometer registers  78°  C.  Collect  the  liq- 
uid which  comes  from  the  condenser. 

a.  What  is  the  smell  and  taste  of  the  liq- 

uid? 

b.  Apply  a  lighted  match  to  a  little  of  it. 

Will  it  burn?* 

c.  What   kind   of   substance   is   formed 

when  yeast  "works,"  or  when  fer- 
mentation takes  place? 

B.  Into  a  half-pint  of  water  put  a  spoonful  of  the 

thin  yeast  mixture  (of  yeast  and  water) ;  set 
aside  in  a  warm  place  beside  the  other  mix- 
ture. Examine  at  the  end  of  12  hours. 

1.  Do  you  see  any  evidence  of  activity  in  the 

mixture? 

2.  What  kind  of  substance  was  present  in  the 

preceding  experiments  which  is  absent  in 
this  experiment? 

3.  What  do  you  infer  from  this  experiment? 

C.  Summary. 

1 .  What  conditions  are  necessary  for  the  rapid 

growth  of  yeast  ? 

2.  What  changes  are  caused  by  the  yeast  in  a 

mixture  in  which  it  is  growing? 

*The  experiment  will  be  more  successful  if  the  liquid  is  distilled 
a  second  time. 


STUDY  OF  TEA8T.  99 

3.  What    substances    are    produced    by    the 

growth  of  yeast? 
D.  Microscopic  study  of  yeast.     (In  class.) 

By  means  of  a  pipette  put  a  drop  from  the 
bottom  of  a  yeast  mixture  on  a  glass  slide; 
cover  with  a  thin  cover-glass,  and  examine 
under  the  high  power  of  the  microscope. 

1.  What  is  the  color  of  the  solid  bodies  (yeast- 

cells)  which  you  see  ? 

2.  Yeast-cells  form  new  cells  by  budding,  the 

bud  (daughter-cell)  usually  remaining 
attached  to  the  cell  (mother-cell)  which 
produced  it. 

a.  Draw   a   group    of   cells    showing   a 
mother-cell  and  two  daughter-cells. 

3.  Can  you  distinguish  a  nucleus  in  any  of  the 

yeast-cells?  (The  colorless  vacuole  is 
not  the  nucleus.) 

4.  Place  a  drop  of  stain  (eosin  or  methyl  vio- 

let) on  the  slide  at  the  edge  of  the  cover- 
glass,  allowing  it  to  run  beneath  the  glass 
to  stain  the  cells.  Can  you  make  out 
any  further  facts  regarding  the  structure 
of  yeast? 

5.  Add  a  drop  of  iodine  to  a  little  yeast  mix- 

ture and  examine  with  the  compound 
microscope.  What  kind  of  bodies  are 
mixed  in  with  the  yeast-cells?  What 
does  their  color  indicate  as  to  their  com- 
position? 


100  LABORATORY  EXERCISES. 


49.   STUDY  OF  BACTERIA. 

Materials  for  home  work  (A,  B) :  Three  bottles  (two  provided 
with  stoppers),  ice-box,  thermometer;  pint  of  milk;  handful  of  dried 
hay. 

Materials  for  class-room  work  (C,  D,  E) :  Arnold  steam  sterilizer, 
flask,  Petri-dishes,  cotton-wool,  inoculator,  compound  microscope 
(500  diameters),  slide,  cover-glass,  eosin,  carbol-fuchsin  or  Lbemers 
blue,  corrosive  sublimate  solution  (1:1000),  made  by  dissolving 
one  antiseptic  tablet  in  a  pint  of  water. 

Nutrient  agar-agar  is  probably  the  best  medium  in  which  to  grow 
all  kinds  of  bacteria.  It  can  be  readily  prepared  in  the  laboratory 
or  home  kitchen  from  the  following  materials:  1000  cc  water,  10 
grams  salt,  10  grams  peptone,  10  grams  Liebig's  beef  extract,  small 
amount  of  cooking  soda,  and  10  grams  agar-agar  (called,  also,  Japan 
isinglass).  If  agar-agar  cannot  be  obtained,  100  grams  of  the  best 
French  gelatin  may  be  used  instead. 

Dissolve  the  beef  extract  in  the  1000  cc.  water.  The  agar,  cut 
into  small  pieces,  is  then  added,  together  with  the  peptone  and  salt. 
The  mixture  should  be  heated  to  cause  the  agar  to  dissolve,  care 
being  taken  that  it  is  not  allowed  to  burn.  Just  enough  cooking 
soda  is  added  to  cause  red  litmus  paper  dipped  in  the  mixture  to 
turn  blue,  that  is,  the  liquid  should  be  faintly  alkaline.  Filtering 
the  hot  agar  sometimes  involves  more  or  less  difficulty.  The  pro- 
cess can  be  easily  carried  on.  however,  within  the  steam  sterilizer. 
A  glass  funnel  should  be  put  in  the  mouth  of  a  Florence  flask  (used 
commonly  in  a  chemical  laboratory) ,  and  one  or  two  layers  of  ab- 
sorbent cotton  placed  within  the  funnel  If  the  agar,  flask,  and 
funnel  are  kept  hot  within  the  sterilizer,  the  liquid  will  readily  pass 
through  the  cotton.  After  filtering,  close  the  mouth  of  the  flask 
with  a  plug  of  absorbent  cotton,  and  boil  in  the  cooker  for  half  an 
hour.  The  flask  may  be  set  aside  as  stock  agar  until  needed  for 
use.  (If  the  agar  mixture  is  not  clear,  it  should  be  filtered  through 
the  same  cotton  a  second  time.)  In  case  any  bacteria  or  mould 
colonies  appear  within  the  flask,  it  should  be  heated  within  the  ster- 
ilizer for  half  an  hour  on  two  or  three  successive  days. 

A.  Growth  of  bacteria  in  hay  infusion  (at  home, . 
i.  Cut  the  hay  into  small  pieces,  place  them  in 
a  mason  jar,  and  half  fill  it  with  water. 


STUDY  OF  BA'Jl'ERTA.  ,  .  101 

Shake  the  mixture  and  put  it  in  a  warm 
place,  noting  the  temperature. 

a.  What  becomes  of  the  hay?     Why? 

b.  What  is  the  color  and  smell  of  the  hay 

infusion  ? 

2.  Examine  the  mixture  after  each  24  hours 
for  a  week. 

a.  What  has  now  become  of  the  hay? 

Why? 

b.  What  change  takes  place  in  the  color 

and  smell  of  the  liquid?     (These 
changes  are  caused  by  bacteria.) 

c.  What  do  you  see  on  the  surface  of  the 

infusion?     (This    is    composed    of 
countless  numbers  of  bacteria.) 
B.  Growth  of  bacteria  in  milk  (at  home). 

Secure  three  clean  bottles  of  about  the  same 
size,  two  of  them  provided  with  stoppers. 

Into  one  of  the  bottles  pour  some  good  fresh 
milk;  cover  and  place  in  the  ice-box,  or  in 
some  other  cold  place.  Label  the  bottle  "  No. 
i." 

Pour  into  the  second  bottle  about  the  same 
amount  of  milk,  and  set  it  aside  in  a  moder- 
ately warm  place,  leaving  it  uncorked.  Note 
the  temperature  by  means  of  a  thermometer. 
Label  "No.  2." 

Clean  the  third  bottle  and  the  cork  in  boiling 
water.  Boil  some  of  the  milk  5  minutes,  and 
pour  it  into  the  bottle  while  hot.  Cork  the 
bottle  and  place  it  beside  the  second  bottle. 
Label  "No.  3,  Sterilized  milk." 


LABORATORY  EXEHCISES. 

Examine  the  three  bottles  of  milk  at  the  end 
of.  12  hours. 

1.  Do  you  notice  any  difference  in  the  smell  or 

taste  of  No.  i,  No.  2,  and  No.  3? 

2.  Boil  the  milk  in  bottle  No.  3  again;  clean 

the  bottle  and  cork  in  boiling  water  as 
before,  and  replace  the  milk  in  the  bottle ; 
cork  the  bottle.  Put  bottle  No.  i  back 
in  the  ice-box ;  return  bottles  No.  2  and 
No.  3  to  the  place  from  which  you  took 
them. 

3.  Examine  all  three  bottles  at  the  end  of  a 

second  12  hours.  Have  any  further 
changes  taken  place? 

4.  Carry  out  the  directions  given  in  2  above  a 

second  time.  Repeat  your  examina- 
tions at  the  end  of  each  successive  12 
hours  for  two  or  three  days,  each  time 
boiling  the  milk  in  bottle  No.  3.  Record 
in  your  note-book  each  time  the  changes 
which  you  observe  in  each  of  the  bottles. 

5.  The  changes  in  the  milk  are  caused  by  the 

growth  of  bacteria  from  the  air  or  on  the 
bottles  or  stoppers. 

a.  What  effect  does  a  cold  temperature 

have  on  the  growth  of  bacteria? 

b.  What  effect  does  boiling  have  on  the 

growth  of  these  cells. 

c.  What  is  the  most  favorable  tempe^a- 

ture  for  the  growth  of  bacteria? 

d.  What  effect  do  some  bacteria  have  on 

the  milk? 


STUDY  OF  BACTERIA.  103 

e.  Compare  the  results  obtained  in  this 
experiment  with  those  already  ob- 
tained   in    the    experiment    with 
yeast. 
C.  Growth  of  bacteria  on  nutrient  agar. 

Pour  a  thin  layer  of  the  nutrient  agar  into 
several  Petri-dishes  which  have  been  heated 
for  a  half -hour  in  the  steam  stenlizer,  quickly 
replacing  the  covers  on  the  dishes,  also  the  cot- 
ton plug  in  the  flask.  Number  the  dishes  1,2, 
etc.,  and  write  date  of  each  part  of  the  experi- 
ment. 

Keep  some  of  the  dishes  carefully  closed 
throughout  the  experiments.  Label  each  of 
these  dishes  "Not  exposed." 

Open  several  of  the  other  dishes,  exposing 
the  gelatin  to  the  air  of  the  room  for  10  min- 
utes. Replace  the  covers,  and  label  each  dish 
"  Exposed  to  the  air  10  minutes." 

Open  the  other  dishes  sufficiently  to  spread 
on  the  surface  a  little  of  the  dust  from  the 
floor  or  from  the  street.  Label  each  dish  "  Ex- 
posed to  dirt." 

Open  a  third  set  of  dishes  of  the  gelatin  and 
pour  on  the  surface  a  thin  layer  of  the  city 
water  obtained  from  the  school  faucets.  Label 
each  "Exposed  to  city  water." 

Set  aside  the  dishes  where  the  temperature 
is  about  70°  F.  Examine  the  dishes  at  the  end 
of  a  day  or  two. 

i.  Do  you  find  any  differences  between  the 
dishes  which  have  been  exposed  to  the 


104:  LABORATORY  EXERCISES. 

air,  the  dirt,  and  the  water,  and  those 
which  have  not  been  exposed? 

2.  Draw  a  figure  of  the  dish  you  are  studying, 

representing  carefully  the  form  and  size 
of  the  spots  (colonies  of  bacteria  or 
mould) . 

3.  Study  the   same  dish  several  days  later. 

Make  a  careful  drawing  as  in  2  above. 
Have  the  colonies  changed  in  size  or  ap- 
pearance since  your  last  study? 

4.  Describe  the  color  of  the  colonies. 

5.  Do  any  of  the  colonies  appear  to  affect  the 

agar  around  them?     (Smell  of  the  agar.) 
D.  Microscopic  study  of  bacteria. 

Carefully  lift  the  cover  from  one  of  the  plates 
of  agar  which  has  been  exposed.  Touch  one 
of  the  colonies  of  bacteria  with  the  point  of  a 
needle,  and  then  rub  the  needle-point  on  a 
clean  glass  slide;  add  a  drop  of  water  to  the 
spot  touched  by  the  needle,  and  cover  with  a 
cover-glass.  Examine  with  the  highest  powers 
of  the  microscope. 

1.  What  is  the  color  of  the  tiny  bodies  (bac- 

teria) which  you  see? 

2.  Do  you  find  more  than  one  kind  of  bacteria  ? 

If  so,  what  is  the  shape  of  each  ? 

3.  Do  any  of  the  bacteria  seem  to  be  in  mo- 

tion? 

4.  Place  a  drop  of  stain  (eosin,  carbol  fuchsin, 

or  LoefHer's  blue)  at  the  side  of  the  cover- 
glass  and  allow  it  to  run  beneath  the 
glass,  staining  the  cells.  Can  you  make 


STUDY  OF  BACTERIA.  105 

out  any  further  points  of  structure  in  the 
bacteria  ? 

E.  Sterilization. 

Prepare  three  dishes  of  nutrient  agar  as  di- 
rected above. 

Remove  the  cover  from  No.  i,  and  allow  it 
to  remain  exposed  to  the  air  for  several  min- 
utes. Label  it  "Agar  No.  i." 

Remove  the  cover  from  a  second  dish,  ex- 
pose it  as  in  No.  i ;  then  pour  over  the  surface 
a  thin  film  of  corrosive  sublimate  (1:1000). 
This  solution  is  made  by  dissolving  one  anti- 
septic tablet  in  a  pint  of  water.  Replace  the 
cover  and  label  "Agar  No.  2  + Poison." 

Expose  a  third  dish  of  agar  to  the  air  for  the 
same  length  of  time  as  in  No.  i  and  No.  2. 
Heat  this  dish  for  a  half -hour  every  12  hours 
in  a  steam  sterilizer  or  over  a  water-bath. 
Label  "Heated  Agar."  Keep  all  three  dishes 
covered,  and  set  them  aside  where  the  tem- 
perature is  about  70°  F. 

Compare  the  three  dishes  at  the  end  of  three 
days. 

1.  What  differences  do  you  notr  between  the 

three  dishes? 

2.  What  is  the  effect  of  the  poison  (corrosive 

sublimate)  on  the  growth  of  bacteria  ? 

3.  What  effect  does  heating  and  cooling  have 

on  the  growth  of  bacteria? 

4.  In  what  two  ways  can  a  substance  be  ster- 

ilized? 

F.  From  all  your  experiments  state — 


106  LABORATORY  EXERCISES. 

1.  What  conditions  seem  to  favor  the  growth 

of  bacteria? 

2.  What  conditions  seem  to  hinder  the  growth 

of  bacteria? 
G.  Practical  questions  in  bacteriology. 

1.  Why  are  fruits  cooked  before  canning? 

2.  Why  should  fruit-jars  be  filled  completely 

before  screwing  on  the  cover? 

3.  Why   do   fruit- jars   sometimes  burst   long 

after  being  filled? 

4.  Why  is  grass  dried  before  it  is  put  into  the 

barn? 

5.  Why  are  milk,  meat,  etc.,  put  in  the  refrig- 

erator in  summer-time? 

6.  Why  should  the  prohibition  against  spit- 

ting in  public  places  be  rigidly  enforced  ? 

7.  Why  should  sweeping  be  done  so  far  as  pos- 

sible without  raising  a  dust  ? 

8.  Why  are  hard-wood  floors  more  healthful 

than  carpets? 

9.  Why  should  the  teeth  be  brushed  often? 

10.  Why  should  the  refuse  be  removed  from  the 

streets  every  morning  early,  especially  in 
summer-time  ? 

11.  Why   should   sink-drains  be   carefully  in- 

spected ? 

12.  Why  should  wounds  be  carefully  cleansed 

and  dressed  at  once? 

13.  Why   are   typhoid   fever,    diphtheria,    and 

other    infectious    diseases    often    better 
treated  in  hospitals? 


STUDY  OF  LIVING   VERTEBRATES.  107 

14.  In  what  ways  do  bacteria  prove  to  be  of 

benefit  'to  mankind  ? 

15.  In  what  ways  do  they  prove  to  be  "man's 

invisible  foes"?  (Read  "The  Story  of 
Bacteria,"  "Dust  and  its  Dangers," 
"  Drinking-water  and  Ice  Supplies,  and 
their  Relations  to  Health  and  Disease," 
by  T.  M.  Prudden,  M.D.  Published  by 
G.  P.  Putnam's  Sons.) 

50.  STUDY  OF  LIVING  VERTEBRATES. 

A.  Habitat. 

1.  Does  the  animal  live  on  land  or  in  water? 

2.  In  what  part  of  the  world  is  it  common? 

3.  What  is  the  climate  of  that  region? 

B.  Locomotion  and  breathing. 

4.  What  appendages  has  the  animal? 

5.  Which  of  these  appendages  are  used  in  lo- 

comotion? 

6.  How  many  digits  of  each  appendage  are 

used? 

7.  What  method  or  methods  of  locomotion 

does  the  animal  have? 

8.  In  proportion  to  its  size  is  its  locomotion 

rapid  or  slow? 

9.  What  other  use  does  the  animal  make  of  its 

appendages? 

10.  What  movements  indicate  that  the  animal 

is  breathing? 
C-  Food-getting. 

11.  What  kind  of  food  (animal  or  vegetable) 

does  it  eat? 


108  LABORATORY  EXERCISE*. 

12.  How  does  the  animal  seize  hold  of  its  food? 

13.  Does  it  chew  its  food  before  swallowing? 

14.  If  possible,  describe  the  teeth. 

D.  Means  of  protection. 

15.  Does  it  have  as  an  outer  covering  hair, 

feathers,  scales,  or  a  naked  skin? 

1 6.  Of  what  use  to  the  animal  is  this  outer  cov- 

ering? 

17.  Is  this  covering  shed  by  the  animal?     If  so, 

when  and  how  ? 

1 8.  What  different  colors  do  you  find  on  the 

animal? 

19.  Do  these  colors  resemble  at  all  the  colors  in 

the  natural  environment  of  the  animal, 
i.e.,  is  the  animal  protectively  colored? 

20.  How  can  the  animal  protect  itself  against 

its  enemies? 

E.  Sense-organs. 

21.  What  is  the  position  of  the  eyes  ?     How  are 

they  protected? 

22.  Locate    the    nostrils.     Do    you    see    them 

close? 

23.  What  evidence  is  there  that  the  animal 

hears?     Can  you  see  any  ears?     If  so, 
describe  them. 


51.   PARTS  OF  A  COMPOUND  MICROSCOPE. 

A.  Base. — This  is  the  solid  foundation  on  which 
the  instrument  rests.     It  is  usually  shaped  like  a 
horseshoe. 

B.  Pillar. — The  vertical  column  which  is  fastened 


PARTS  OF  A  COMPOUND  MICROSCOPE.      103 


M 


FIG.  8. 


110  LABORATORY  EXERCISES. 

to  the  base  and  which  carries  upon  its  upper  end  the 
joint  provided  for  inclining  the  instrument. 

C.  Arm. — This  supports  all  the  upper  parts  of  the 
instrument. 

D.- Body. — The  tube  portion  to  which  are  at- 
tached the  magnifying  parts  of  the  microscope. 

E.  Nose-piece. — This  is  an   extra  piece  attached 
to  the  lower  part  of  the  body,  which  provides  a 
means  of  quickly  changing  the  objectives. 

F.  Objectives. — These    are    the    most    important 
magnifying  parts  of  the  microscope.     They  are  so 
called  because  they  are  nearest  the  object  that  is 
being  examined.     The  shorter  objective  is  called  the 
low  power,  because  it  magnifies  least.     The  longer 
objective  is  the  high  power. 

G.  Eyepiece. — It  is  so  called  because  it  is  nearest 
the  eye.     The  eyepiece  magnifies  the  image  formed 
by  the  objective. 

H.  Draw-tube—  This  is  the  portion  of  the  body 
which  moves  in  the  outer  sheath  and  which  receives 
the  eyepiece.  If  the  tube  is  drawn  upward  the 
magnifying  power  of  the  microscope  is  increased. 

1.  Collar. — A  nng  attached  to  the  draw-tube.  It 
is  usually  provided  with  a  milled  edge. 

J.  Coarse  Adjustment. — This  is  a  provision  for 
moving  the  body  of  the  microscope  up  and  down  by 
means  of  a  so-called  rack  and  pinion. 

K.  Milled  Heads. — The  wheels  on  either  side  of 
the  coarse  adjustment.  When  the  wheels  are  turned 
toward  the  observer  the  body  carrying  the  magni- 
fying parts  is  raised. 

L.  Fine  Adjustment. — This  horizontal  wheel  is  at- 


PARTS  OF  A   COMPOUND  MICROSCOPE.         Ill 

tached  to  a  fine  screw.  When  it  is  turned  in  the  di- 
rection of  the  hands  of  a  clock  the  body  is  lowered 
very  slowly.  By  turning  in  the  opposite  direction 
the  magnifying  parts  are  raised. 

M.  Stage. — This  is  the  part  on  which  the  slide 
with  the  object  is  placed  for  examination.  It  is  at- 
tached to  the  arm. 

N.  Clips. — Two  springs  which  are  attached  to  the 
upper  surface  of  the  stage  and  which  serve  to  hold 
the  slide  in  place. 

O.  Mirror. — The  mirror  is  used  for  reflecting  the 
light  upon  the  object.  The  flat  surface  is  called  the 
plane  mirror.  The  hollow  surface  is  the  concave 
mirror.  The  latter  not  only  reflects  but  also  con- 
centrates light  upon  the  object. 

P.  Mirror  Bar. — This  bar  carries  the  mirror.  It 
can  be  turned  so  as  to  throw  light  upon  the  object 
from  any  direction. 

Q.  Substage. — An  arrangement  below  the  stage 
to  receive  various  extra  devices  for  increasing  or 
regulating  the  amount  of  light. 

S.  Iris  Diaphragm. — This  device  enables  one  to 
shut  off  or  increase  the  amount  of  light  that  falls 
upon  the  object.  When  the  small  lever  beneath  the 
stage  is  moved  toward  the  right  the  hole  through  the 
stage  is  diminished  in  size. 


112  LABORATORY  EXERCISES. 


52.    RULES  FOR  THE  USE  OF  THE  COM- 
POUND MICROSCOPE. 

I.  To  lift  the  microscope,  always  grasp  it  firmly  by 

the  pillar  beneath  the  stage. 

II.  To  use  the  low  power-objective. 

1 .  Place  the  stand  so  the  two  arms  of  the  base 

face  the  window.  Keep  the  microscope 
out  of  the  direct  sunlight. 

2.  See  that  the  nose-piece  is  in  the  position 

which  will  bring  the  low-power  objective 
over  the  opening  in  the  stage. 

3.  Move  the  tube  up  or  down  by  the  coarse  ad- 

justment until  the  lower  end  of  the  low- 
power  objective  is  a  little  more  than  a 
quarter  of  an  inch  above  the  level  of  the 
stage. 

4.  See  that  the  plane  side  of  the  mirror  is  fac- 

ing the  source  of  light.  Looking  down 
through  the  tube,  move  the  mirror  about 
until  the  field  of  the  microscope  has  the 
best  possible  illumination.  (The  field  of 
the  microscope  is  the  lighted  circular 
area  which  appears  when  looking  down 
through  the  tube.) 

5.  Place  the  slide  on  the  stage  (cover-glass  on 

top)  in  a  position  so  the  object  to  be  ex- 
amined is  over  the  centre  of  the  hole  in 
the  stage.  Fix  the  slide  in  place  with 
the  clips. 

6.  Look  through   the  microscope  and  slowly 


RULES  FOR   USE  OF  COMPOUND  MICROSCOPE.  113 

move  the  tube  up  by  turning  the  coarse 
adjustment  until  the  object  is  seen  as 
clearly  as  possible.  Be  careful  never  to 
push  the  tube  down  so  the  objective 
touches  the  slide. 
7.  In  examining  a  slide,  focus  the  tube  by 

means  of  the  fine  adjustment. 
III.   To  use  the  high-power  objective. 

1.  Place  the  slide  upon  the  stage  and  focus 

upon  it  with  the  low -power  objective  as 
directed  in  II  above. 

2.  Turn   the   mirror  so   the   concave   surface 

faces  the  source  of  light.  Looking 
through  the  tube,  move  the  mirror  about 
until  the  field  of  the  microscope  has  the 
best  illumination. 

3.  Place  the  eye  at  the  level  of  the  stage  and 

carefully  turn  the  nose-piece  so  the  high- 
power  objective  is  brought  into  position 
above  the  hole  in  the  stage.  If  the 
lower  end  of  the  objective  touches  the 
cover-glass,  turn  the  fine  adjustment 
screw  in  a  direction  opposite  to  that  of 
the  hands  of  a  clock. 

4.  When  the  objective  is  in  position  look  at 

the  object  through  the  microscope  and 
focus  slowly  with  the  fine  adjustment- 
screw  until  the  image  is  clearest.  Take 
great  care,  as  directed  in  3  above,  to  see 
that  the  objective  does  not  touch  the 
cover-glass. 

5.  After  using  the  high-power  objective,  turn 


LABORATORY  EXERCISES. 


the  nose-piece  so  as  to  leave  the  low- 
power  objective  in  position  over  the 
diaphragm. 

IV.  The  pupil  should  learn  to  look  through  the 

microscope  using  the  right  and  left  eye 
alternately.  Both  eyes  should  remain 
open. 

V.  Table    of    approximate    magnifications    of    the 

Bausch  &  Lomb  microscopes: 


1 

Objective 
.     2-inch 

Eyepiece. 
2-inch          Ab 
1-inch 
2-inch 
1-inch 
2-inch 
1-inch 
2-inch 
1-inch 

Magnification, 
out     15  diameters. 
30 
50 
100        " 
250        " 
450        " 
600        " 
1100        " 

2  .  . 

.  .  .   2-inch 

3 

§-inch 

4  .  . 

.   §-inch 

5 

^-inch 

6  .. 

.  .  .   J-inch 

7 

rs-inch 

8  , 

.  .TV-inch 

LIST  OF  APPARATUS  AND  CHEMICALS  RE- 
QUIRED TO  SUPPLY  A  CLASS  OF  TWENTY- 
FOUR. 

An  articulated  skeleton  can  be  obtained  of  the  Kny- 
Scheerer  Co.,  225  Fourth  Avenue,  New  York  City,  for  $25. 
Large  physiological  wall-charts  are  most  useful  in  oral  reci- 
tations. Those  made  by  L.  W.  Joutel,  164  E.  117th  St., 
New  York  City,  cost  $10  to  $15  each,  but  they  have  been 
found  invaluable  as  a  means  of  demonstration.  The 
micro-photographs  prepared  by  W.  H.  "Walmsley,  4248 
Pine  St.,  Philadelphia,  Pa.,  are  also  of  great  assistance  in 
teaching  the  minute  anatomy  of  various  organs  and  tis- 
sues. In  large  quantities  these  prints  (unmounted)  cost 
about  10  cents  each. 

The  following  supplies  will  be  furnished  to  schools  by 
Bausch  &  Lomb  Optical  Co.,  1123  Broadway,  New  York 
City,  at  the  special  prices  quoted.  (The  numbers  and  let- 
ters refer  to  Bausch  &  Lomb's  Catalogue.). 

1  Compound  microscope  Bl,  witli  f"  and  |"  objectives.  $23  50 

24  Magnifiers,  5-10"  diameter,  QR 6  30 

1  Weighing  balance,  No.  8104 12  50 

24  Evaporating  dishes  (porcelain),  No.  10034,  45  cc 2  50 

24  Alcohol-lamps,  No.  8470,  100  cc 9  00 

1  Gross  slides,  No.  1290 75 

1  oz.  round  cover-glasses,  f",  No.  1274 75 

24  Scalpels,  No.  1450 6  30 

24  Pairs  forceps,  straight,  No.  1400 450 

24  Pairs  dissecting  scissors,  No.  1550 9  00 

115 


116         LIST  OF  APPARATUS  AND   CHEMICALS. 

50  Dissecting  needles,  No.  1516  • $1  13 

144  Test-tubes,  No.  9460,  150  x  15  ram 216 

1  Chemical  thermometer,  No.  9760  B 94 

1  Lactometer,  No.  9892 38 

12  Iron  apparatus  stands,  three  rings,  No.  10216 5  85 

24  Pieces  wire  gauze,  3"  x  3",  No.  9840,  per  Ib 38 

24  Glass  stirring  rods,  No.  9326,  per  Ib 38 

10  Ft.  glass  tubing,  5  mm.,  No.  9320,  per  Ib 30 

6  Thistle  tubes,  300  mm. ,  No.  9242 45 

6  Beaker  glasses,  No.  8916,  200  cc 90 

1  Glass  bottle,  No.  8958,  3  oz.,  with  rubber  cork,  No. 

10126,  with  two  perforations 10 

1  Bell  jar,  No.  8932,  with  opening  at  top,  200  x  150  mm.  7o 

1  Piece  of  sheet  rubber,  1  ft.  x  1  ft.,  per  Ib 1  50 

2  Flasks,  No.  9192,  250  cc 23 

pair  of  bone  forceps,  No.  1374 1  88 

Bone  saw,  No.  1536 3  00 

Probes,  No.  1590 180 

Cylindrical  graduate,  No.  9660,  250  cc 57 

Piece  platinum  foil,  1"  x  1",  No.  9960,  per  grm 75 

Box  slide  labels,  No.  1762 8 

1  Arnold  steam  sterilizer,  No.  6038A,  heavy  tin,  copper 

bottom . .    3  75 

24  Petri  dishes,  80  mm.,  No.  9150 3  60 

1  Distilling  apparatus,  Muencke's,  of  glass  with  ground 

joints,  500  cc 6  00 

CHEMICALS. 

4-  Ib.  hydrochloric  acid,  c.  p.  500  cc.,  S.  G.  1.190 22 

%  "  nitric  acid  (cone.),  c.  p.  500  cc.,  S.  G.  1.425 23 

i  "  ammonia  (cone.),  c.  p.  500  cc.,  S.  G.  0.90 21 

i   "  sulphuric  acid,  500  cc.,  S.  G.  1.840 19 

1  oz.  iodine,  pure,  resublimed 48 

5    "   potassium  iodide 1  35 

±  Ib.  ether  sulphuris,  250  cc.,  S.  G.  0.722 28 

5  gr.  caustic  potash,  white  sticks 10 

5   "       "       soda,  purified  sticks 10 

100  cc.  lime-water 10 


LIST  OF  APPARATUS  AND   CHEMICALS.  117 

100  pieces  red  litmus  paper,  2"  x  i",  No.  7600 ...    $010 

100      "     blue  litmus  paper,  2"  x  ±",  No.  7600 10 

4  gr.  quinine 20 

500  cc.  95#  alcohol,  deodorized 58 

100  cc.  glycerin,  refined,  white 17 

5  gr.  pancreatin  (Fairchild) ; 20 

5   "  ox-gall 10 

5  "  pepsin,  powder 10 

10  gr.  common  salt 05 

1   "  phosphate  of  lime,  c.  p 10 

10  "  glucose,  crystallized,  pure 10 

500  cc.  Fehling  solution 83 

10  gr.  eosin,  yellowish,  dry 23 

10  "  methyl  violet,  dry 23 

1  Ib.  agar  agar,  best  quality,  in  shreds 40 

12  gr.  peptone  (U.  S.),  pure 25 

2  Ibs.  formaldehyde,  40£ 85 

1  stick  phosphorus 10 

|  Ib.  sulphur  flowers 10 

i  Ib.  chlorate  potash,  pure  crystals 15 

£  Ib.  oxid  of  manganese,  pulverized 10 

24  small  pieces  zinc,  |"  square 10 

1  Ib.  cotton  wool 38 

1  oz.  potassium  permanganate 10 


BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN     INITIAL    FINE     OF    25     CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


. 


AP»  25  1! 

ON    7    1933 


NOV  28  1938 
6  1941 


FEE  20  1941 
MAR    5  1941 


31964 


LD  21-50m-l.'33 


304680 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


